--- a/testing/mozharness/configs/merge_day/aurora_to_beta.py
+++ b/testing/mozharness/configs/merge_day/aurora_to_beta.py
@@ -56,16 +56,17 @@ config = {
         ("build/mozconfig.common",
          "MOZ_REQUIRE_SIGNING=${MOZ_REQUIRE_SIGNING-0}",
          "MOZ_REQUIRE_SIGNING=${MOZ_REQUIRE_SIGNING-1}"),
         ("build/mozconfig.common",
          "# Disable enforcing that add-ons are signed by the trusted root",
          "# Enable enforcing that add-ons are signed by the trusted root")
     ],
 
+    "use_vcs_unique_share": True,
     "vcs_share_base": os.path.join(ABS_WORK_DIR, 'hg-shared'),
     # "hg_share_base": None,
     "tools_repo_url": "https://hg.mozilla.org/build/tools",
     "tools_repo_branch": "default",
     "from_repo_url": "ssh://hg.mozilla.org/releases/mozilla-aurora",
     "to_repo_url": "ssh://hg.mozilla.org/releases/mozilla-beta",
 
     "base_tag": "FIREFOX_BETA_%(major_version)s_BASE",

--- a/testing/mozharness/configs/merge_day/beta_to_release.py
+++ b/testing/mozharness/configs/merge_day/beta_to_release.py
@@ -24,16 +24,17 @@ config = {
         ("browser/confvars.sh",
          "ACCEPTED_MAR_CHANNEL_IDS=firefox-mozilla-beta,firefox-mozilla-release",
          "ACCEPTED_MAR_CHANNEL_IDS=firefox-mozilla-release"),
         ("browser/confvars.sh",
          "MAR_CHANNEL_ID=firefox-mozilla-beta",
          "MAR_CHANNEL_ID=firefox-mozilla-release"),
     ],
 
+    "use_vcs_unique_share": True,
     "vcs_share_base": os.path.join(ABS_WORK_DIR, 'hg-shared'),
     # "hg_share_base": None,
     "tools_repo_url": "https://hg.mozilla.org/build/tools",
     "tools_repo_branch": "default",
     "from_repo_url": "ssh://hg.mozilla.org/releases/mozilla-beta",
     "to_repo_url": "ssh://hg.mozilla.org/releases/mozilla-release",
 
     "base_tag": "FIREFOX_RELEASE_%(major_version)s_BASE",

--- a/testing/mozharness/configs/merge_day/bump_esr.py
+++ b/testing/mozharness/configs/merge_day/bump_esr.py
@@ -1,12 +1,13 @@
 import os
 
 ABS_WORK_DIR = os.path.join(os.getcwd(), "build")
 config = {
+    "use_vcs_unique_share": True,
     "vcs_share_base": os.path.join(ABS_WORK_DIR, 'hg-shared'),
     "log_name": "bump_esr",
     "version_files": [
         {"file": "browser/config/version.txt", "suffix": ""},
         {"file": "browser/config/version_display.txt", "suffix": ""},
         {"file": "config/milestone.txt", "suffix": ""},
     ],
     "tools_repo_url": "https://hg.mozilla.org/build/tools",

--- a/testing/mozharness/configs/merge_day/central_to_aurora.py
+++ b/testing/mozharness/configs/merge_day/central_to_aurora.py
@@ -64,16 +64,17 @@ config = {
     ],
     "locale_files": [
         "browser/locales/shipped-locales",
         "browser/locales/all-locales",
         "mobile/android/locales/maemo-locales",
         "mobile/android/locales/all-locales"
     ],
 
+    "use_vcs_unique_share": True,
     "vcs_share_base": os.path.join(ABS_WORK_DIR, 'hg-shared'),
     # "hg_share_base": None,
     "tools_repo_url": "https://hg.mozilla.org/build/tools",
     "tools_repo_branch": "default",
     "from_repo_url": "ssh://hg.mozilla.org/mozilla-central",
     "to_repo_url": "ssh://hg.mozilla.org/releases/mozilla-aurora",
 
     "base_tag": "FIREFOX_AURORA_%(major_version)s_BASE",

--- a/testing/mozharness/configs/merge_day/release_to_esr.py
+++ b/testing/mozharness/configs/merge_day/release_to_esr.py
@@ -16,16 +16,17 @@ config = {
         # File, from, to
         ("browser/confvars.sh",
          "ACCEPTED_MAR_CHANNEL_IDS=firefox-mozilla-release",
          "ACCEPTED_MAR_CHANNEL_IDS=firefox-mozilla-esr"),
         ("browser/confvars.sh",
          "MAR_CHANNEL_ID=firefox-mozilla-release",
          "MAR_CHANNEL_ID=firefox-mozilla-esr"),
     ],
+    "use_vcs_unique_share": True,
     "vcs_share_base": os.path.join(ABS_WORK_DIR, 'hg-shared'),
     # "hg_share_base": None,
     "tools_repo_url": "https://hg.mozilla.org/build/tools",
     "tools_repo_branch": "default",
     "from_repo_url": "ssh://hg.mozilla.org/releases/mozilla-release",
     "to_repo_url": NEW_ESR_REPO,
 
     "base_tag": "FIREFOX_ESR_%(major_version)s_BASE",

--- a/testing/mozharness/configs/merge_day/staging_beta_migration.py
+++ b/testing/mozharness/configs/merge_day/staging_beta_migration.py
@@ -4,16 +4,17 @@
 #   mozharness/configs/merge_day/staging_beta_migration.py ...
 import os
 
 ABS_WORK_DIR = os.path.join(os.getcwd(), "build")
 
 config = {
     "log_name": "staging_beta",
 
+    "use_vcs_unique_share": True,
     "vcs_share_base": os.path.join(ABS_WORK_DIR, 'hg-shared'),
     "tools_repo_url": "https://hg.mozilla.org/build/tools",
     "tools_repo_branch": "default",
     "from_repo_url": "ssh://hg.mozilla.org/releases/mozilla-aurora",
     "to_repo_url": "ssh://hg.mozilla.org/users/stage-ffxbld/mozilla-beta",
 
     "base_tag": "FIREFOX_BETA_%(major_version)s_BASE",
     "end_tag": "FIREFOX_BETA_%(major_version)s_END",

--- a/testing/mozharness/mozharness/base/vcs/mercurial.py
+++ b/testing/mozharness/mozharness/base/vcs/mercurial.py
@@ -7,16 +7,17 @@
 """Mercurial VCS support.
 """
 
 import os
 import re
 import subprocess
 from collections import namedtuple
 from urlparse import urlsplit
+import hashlib
 
 import sys
 sys.path.insert(1, os.path.dirname(os.path.dirname(os.path.dirname(sys.path[0]))))
 
 import mozharness
 from mozharness.base.errors import HgErrorList, VCSException
 from mozharness.base.log import LogMixin, OutputParser
 from mozharness.base.script import ScriptMixin
@@ -349,16 +350,20 @@ class MercurialVCS(ScriptMixin, LogMixin
         # scripts that have multiple repos. This includes the clone_tools()
         # step :(
 
         if not rev and not branch:
             self.warning('did not specify revision or branch; assuming "default"')
             branch = 'default'
 
         share_base = c.get('vcs_share_base', os.environ.get('HG_SHARE_BASE_DIR', None))
+        if share_base and c.get('use_vcs_unique_share'):
+            # Bug 1277041 - update migration scripts to support robustcheckout
+            # fake a share but don't really share
+            share_base = os.path.join(share_base, hashlib.md5(dest).hexdigest())
 
         # We require shared storage is configured because it guarantees we
         # only have 1 local copy of logical repo stores.
         if not share_base:
             raise VCSException('vcs share base not defined; '
                                'refusing to operate sub-optimally')
 
         if not self.robustcheckout_path:

--- a/testing/mozharness/scripts/merge_day/gecko_migration.py
+++ b/testing/mozharness/scripts/merge_day/gecko_migration.py
@@ -172,21 +172,17 @@ class GeckoMigration(MercurialScript, Ba
     def query_commit_message(self):
         return "Update configs. IGNORE BROKEN CHANGESETS CLOSED TREE NO BUG a=release ba=release"
 
     def query_push_dirs(self):
         dirs = self.query_abs_dirs()
         return dirs.get('abs_from_dir'), dirs.get('abs_to_dir')
 
     def query_push_args(self, cwd):
-        if cwd == self.query_abs_dirs()['abs_to_dir'] and \
-                self.config['migration_behavior'] == 'beta_to_release':
-            return ['--new-branch']
-        else:
-            return []
+        return ['-r', '.']
 
     def query_from_revision(self):
         """ Shortcut to get the revision for the from repo
             """
         dirs = self.query_abs_dirs()
         return self.query_hg_revision(dirs['abs_from_dir'])
 
     def query_to_revision(self):