--- a/build/check-sync-exceptions
+++ b/build/check-sync-exceptions
@@ -3,16 +3,19 @@ mach_bootstrap.py
 merge-installrdf.py
 pymake
 client.py-args
 client.py-l10n-args
 configobj.py
 mozconfig.comm-support
 virtualenv_packages.txt
 
+# Use comm-central buckets for ccache.
+mozconfig.cache
+
 # Ignore detritus left lying around by editing tools.
 *~
 .#*
 #*#
 *.orig
 *.rej
 
 # Ignore "compiled" python files

--- a/build/mozconfig.cache
+++ b/build/mozconfig.cache
@@ -2,55 +2,18 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 # Setup for build cache
 
 # Avoid duplication if the file happens to be included twice.
 if test -z "$bucket" -a -z "$NO_CACHE"; then
 
-# buildbot (or builders that use buildprops.json):
-if [ -f $topsrcdir/../buildprops.json ]; then
-read branch platform master <<EOF
-$(python2.7 -c 'import json; p = json.loads(open("'"$topsrcdir"'/../buildprops.json").read())["properties"]; print p["branch"], p["platform"], p["master"]' 2> /dev/null)
-EOF
-
-bucket=
+# builds where buildprops didn't have the data (eg: taskcluster or non-buildbot) and without sccache disabled:
 if test -z "$SCCACHE_DISABLE"; then
-    case "${branch}" in
-    try)
-        case "${master}" in
-        *scl1.mozilla.com*|*.scl3.mozilla.com*)
-            bucket=mozilla-releng-s3-cache-us-west-1-try
-            ;;
-        *use1.mozilla.com*)
-            bucket=mozilla-releng-s3-cache-us-east-1-try
-            ;;
-        *usw2.mozilla.com*)
-            bucket=mozilla-releng-s3-cache-us-west-2-try
-            ;;
-        esac
-        ;;
-    autoland|mozilla-inbound)
-        case "${master}" in
-        *use1.mozilla.com*)
-            bucket=mozilla-releng-s3-cache-us-east-1-prod
-            ;;
-        *usw2.mozilla.com*)
-            bucket=mozilla-releng-s3-cache-us-west-2-prod
-            ;;
-        esac
-        ;;
-    esac
-fi
-fi
-
-# builds where buildprops didn't have the data (eg: taskcluster or non-buildbot) and without sccache disabled:
-if test -z "$bucket" -a -z "$SCCACHE_DISABLE"; then
-
     # prevent rerun if az is set, or wget is not available
     if test -z "$availability_zone" -a -x "$(command -v wget)"; then
         if test -n "${TASKCLUSTER_WORKER_GROUP}"; then
             # TASKCLUSTER_WORKER_GROUP is just the region now, so
             # stick an extra character on to make the already-convoluted logic
             # here simpler.
             availability_zone="${TASKCLUSTER_WORKER_GROUP}x"
         else
@@ -59,69 +22,38 @@ if test -z "$bucket" -a -z "$SCCACHE_DIS
             availability_zone=$(wget -T 1 -t 1 -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone || true)
         fi
         if test -z "$availability_zone" -o "$availability_zone" = "not-ec2"; then
             availability_zone=not-ec2
         else
             # region is az with last letter trimmed
             region=${availability_zone%?}
             # set S3 bucket according to tree (level)
-            case "${GECKO_HEAD_REPOSITORY}" in
-            *hg.mozilla.org/try*)
-                bucket=taskcluster-level-1-sccache-${region}
-                ;;
-            *hg.mozilla.org/integration/autoland*|*hg.mozilla.org/integration/mozilla-inbound*)
-                bucket=taskcluster-level-3-sccache-${region}
+            case "${COMM_HEAD_REPOSITORY}" in
+            *hg.mozilla.org/try-comm-central*)
+                bucket=comm-central-level-1-sccache-${region}
                 ;;
-            esac
-
-            # set a dummy master
-            case "${region}" in
-            eu-central-1)
-                master=dummy.euc1.mozilla.com
-                ;;
-            us-east-1)
-                master=dummy.use1.mozilla.com
-                ;;
-            us-west-1)
-                master=dummy.usw1.mozilla.com
-                ;;
-            us-west-2)
-                master=dummy.usw2.mozilla.com
+            *hg.mozilla.org/comm-central*)
+                bucket=comm-central-level-3-sccache-${region}
                 ;;
             esac
         fi
     fi
 fi
 
-# if platform hasn't been determined from buildprops, and we're on windows,
-# it must be set to prevent adding ac_add_options --with-ccache below
-if test -z "$platform"; then
-    # set platform based on the SYSTEMROOT env var
+if test -z "$bucket"; then
+    # if we're on windows, disable ccache
     case "${SYSTEMROOT}" in
-    *Windows)
-        platform=windows
-        suffix=.exe
-        ;;
-    esac
-fi
-
-if test -z "$bucket"; then
-    case "$platform" in
-    win*) : ;;
+    *Windows) : ;;
     *)
         export CCACHE=ccache
     esac
 else
     mk_add_options "export SCCACHE_BUCKET=$bucket"
-    case "$master" in
-    *us[ew][12].mozilla.com*|*euc1.mozilla.com*)
-        mk_add_options "export SCCACHE_NAMESERVER=169.254.169.253"
-        ;;
-    esac
+    mk_add_options "export SCCACHE_NAMESERVER=169.254.169.253"
     export CCACHE="$topsrcdir/sccache2/sccache${suffix}"
     export SCCACHE_VERBOSE_STATS=1
     mk_add_options MOZBUILD_MANAGE_SCCACHE_DAEMON=${topsrcdir}/sccache2/sccache
     mk_add_options "UPLOAD_EXTRA_FILES+=sccache.log.gz"
     case "$platform" in
     win*)
         # sccache supports a special flag to create depfiles.
         #TODO: bug 1318370 - move this all into toolchain.configure

--- a/mail/config/mozconfigs/linux32/debug
+++ b/mail/config/mozconfigs/linux32/debug
@@ -20,9 +20,9 @@ export MOZ_DEBUG_SYMBOLS=1
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
-. "$topsrcdir/build/mozconfig.cache"
+. "$commtopsrcdir/build/mozconfig.cache"

--- a/mail/config/mozconfigs/linux32/nightly
+++ b/mail/config/mozconfigs/linux32/nightly
@@ -26,9 +26,9 @@ MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
 mk_add_options "export SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE=/builds/crash-stats-api.token"
 
-. "$topsrcdir/build/mozconfig.cache"
+. "$commtopsrcdir/build/mozconfig.cache"

--- a/mail/config/mozconfigs/linux64/debug
+++ b/mail/config/mozconfigs/linux64/debug
@@ -20,9 +20,9 @@ export MOZ_DEBUG_SYMBOLS=1
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
-. "$topsrcdir/build/mozconfig.cache"
+. "$commtopsrcdir/build/mozconfig.cache"

--- a/mail/config/mozconfigs/linux64/nightly
+++ b/mail/config/mozconfigs/linux64/nightly
@@ -26,9 +26,9 @@ MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
 mk_add_options "export SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE=/builds/crash-stats-api.token"
 
-. "$topsrcdir/build/mozconfig.cache"
+. "$commtopsrcdir/build/mozconfig.cache"

--- a/mail/config/mozconfigs/macosx64/debug
+++ b/mail/config/mozconfigs/macosx64/debug
@@ -14,18 +14,17 @@ export MOZ_DEBUG_SYMBOLS=1
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
-. "$topsrcdir/build/mozconfig.cache"
-
+. "$commtopsrcdir/build/mozconfig.cache"
 
 if [ "$MOZ_IS_COMM_TOPDIR" = "1" ]; then
   # XXX hack to work around dsymutil failing on OSX builds (bug 1380381, 1382262)
   ac_add_options RUSTFLAGS='-C debuginfo=1'
 
   # https://bugzilla.mozilla.org/show_bug.cgi?id=1424825
   mk_add_options "CLIENT_PY_ARGS += --fixup-rust-vendoring-bug-1424825"
 fi

--- a/mail/config/mozconfigs/macosx64/nightly
+++ b/mail/config/mozconfigs/macosx64/nightly
@@ -18,17 +18,17 @@ export MOZ_TELEMETRY_REPORTING=1
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
-. "$topsrcdir/build/mozconfig.cache"
+. "$commtopsrcdir/build/mozconfig.cache"
 
 if [ "$MOZ_IS_COMM_TOPDIR" = "1" ]; then
   # XXX hack to work around dsymutil failing on OSX builds (bug 1380381, 1382262)
   ac_add_options RUSTFLAGS='-C debuginfo=1'
 
   # https://bugzilla.mozilla.org/show_bug.cgi?id=1424825
   mk_add_options "CLIENT_PY_ARGS += --fixup-rust-vendoring-bug-1424825"
 fi

--- a/mail/config/mozconfigs/win32/debug
+++ b/mail/config/mozconfigs/win32/debug
@@ -15,16 +15,18 @@ export MOZ_DEBUG_SYMBOLS=1
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
+. "$commtopsrcdir/build/mozconfig.cache"
+
 . $topsrcdir/build/win32/mozconfig.vs-latest
 
 # Set up mapi includes (must be done after visual studio setup)
 export INCLUDE=$INCLUDE:/c/Office\ 2010\ Developer\ Resources/Outlook\ 2010\ MAPI\ Headers
 mk_export_correct_style INCLUDE
 
 if [ "$MOZ_IS_COMM_TOPDIR" == "1" ]; then
   # Use the TOOLTOOL provided xz for mar generation.

--- a/mail/config/mozconfigs/win32/nightly
+++ b/mail/config/mozconfigs/win32/nightly
@@ -19,16 +19,18 @@ export MOZILLA_OFFICIAL=1
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
+. "$commtopsrcdir/build/mozconfig.cache"
+
 . $topsrcdir/build/win32/mozconfig.vs-latest
 
 # Set up mapi includes (must be done after visual studio setup)
 export INCLUDE=$INCLUDE:/c/Office\ 2010\ Developer\ Resources/Outlook\ 2010\ MAPI\ Headers
 mk_export_correct_style INCLUDE
 
 if [ "$MOZ_IS_COMM_TOPDIR" == "1" ]; then
   # Use the TOOLTOOL provided xz for mar generation.

--- a/mail/config/mozconfigs/win64/debug
+++ b/mail/config/mozconfigs/win64/debug
@@ -15,16 +15,18 @@ export MOZILLA_OFFICIAL=1
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
+. "$commtopsrcdir/build/mozconfig.cache"
+
 . $topsrcdir/build/win64/mozconfig.vs-latest
 
 # Set up mapi includes (must be done after visual studio setup)
 export INCLUDE=$INCLUDE:/c/Office\ 2010\ Developer\ Resources/Outlook\ 2010\ MAPI\ Headers
 mk_export_correct_style INCLUDE
 
 if [ "$MOZ_IS_COMM_TOPDIR" == "1" ]; then
   # Use the TOOLTOOL provided xz for mar generation.

--- a/mail/config/mozconfigs/win64/nightly
+++ b/mail/config/mozconfigs/win64/nightly
@@ -19,16 +19,18 @@ export MOZ_TELEMETRY_REPORTING=1
 # Disable checking that add-ons are signed by the trusted root
 MOZ_ADDON_SIGNING=0
 # Disable enforcing that add-ons are signed by the trusted root
 MOZ_REQUIRE_ADDON_SIGNING=0
 
 # Package js shell
 export MOZ_PACKAGE_JSSHELL=1
 
+. "$commtopsrcdir/build/mozconfig.cache"
+
 . $topsrcdir/build/win64/mozconfig.vs-latest
 
 # Set up mapi includes (must be done after visual studio setup)
 export INCLUDE=$INCLUDE:/c/Office\ 2010\ Developer\ Resources/Outlook\ 2010\ MAPI\ Headers
 mk_export_correct_style INCLUDE
 
 if [ "$MOZ_IS_COMM_TOPDIR" == "1" ]; then
   # Use the TOOLTOOL provided xz for mar generation.