--- a/build/mozconfig.cache
+++ b/build/mozconfig.cache
@@ -38,20 +38,20 @@ if test -z "$SCCACHE_DISABLE" -a -z "$no
             bucket=mozilla-releng-s3-cache-us-west-2-prod
             ;;
         esac
         ;;
     esac
 fi
 
 # taskcluster:
-else
+elif test -z "$CCACHE_DIR"; then
     # timeout after 1 second, and don't retry (failure indicates instance is not in ec2 or wget, network issue)
     # availability_zone is of the form <region><letter> where region is e.g. us-west-2, and az is us-west-2a
-    availability_zone=$(wget -T 1 -t 1 -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone)
+    availability_zone=$(wget -T 1 -t 1 -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone || true)
     # region is az with last letter trimmed
     region=${availability_zone%?}
     if test -z "$SCCACHE_DISABLE" -a -z "$no_sccache" -a -z "$MOZ_PGO_IS_SET" -a -z "$MOZ_PGO"; then
         # set S3 bucket according to tree (level)
         case "${GECKO_HEAD_REPOSITORY}" in
         *hg.mozilla.org/try*)
             bucket=taskcluster-level-1-sccache-${region}
             ;;