rename from .gecko_ref.yml
rename to .gecko_rev.yml
--- a/.gecko_ref.yml
+++ b/.gecko_rev.yml
@@ -1,9 +1,14 @@
 ---
 GECKO_BASE_REPOSITORY: https://hg.mozilla.org/mozilla-unified
 GECKO_HEAD_REPOSITORY: https://hg.mozilla.org/mozilla-central
-GECKO_HEAD_REF: default
+GECKO_HEAD_REV: default
 
 ### For branches
 # GECKO_BASE_REPOSITORY: https://hg.mozilla.org/mozilla-unified
 # GECKO_HEAD_REPOSITORY: https://hg.mozilla.org/releases/mozilla-beta
-# GECKO_HEAD_REF: 8574d2808aaa
+# GECKO_HEAD_REV: 8574d2808aaa
+#
+# Note about GECKO_HEAD_REV vs GECKO_HEAD_REF:
+# GECKO_HEAD_REF is deprecated. Please use GECKO_HEAD_REV only.
+# "default" is a special case and is considered a valid revision for
+# our purposes.

--- a/.taskcluster.yml
+++ b/.taskcluster.yml
@@ -142,17 +142,16 @@ tasks:
 
       payload:
         env:
           # checkout-gecko uses these to check out the source; the inputs
           # to `mach taskgraph decision` are all on the command line.
           $merge:
             - COMM_BASE_REPOSITORY: 'https://hg.mozilla.org/comm-central'
               COMM_HEAD_REPOSITORY: '${repoUrl}'
-              COMM_HEAD_REF: '${push.revision}'
               COMM_HEAD_REV: '${push.revision}'
               HG_STORE_PATH: /builds/worker/checkouts/hg-store
               TASKCLUSTER_CACHES: /builds/worker/checkouts
               # someday, these will be provided by the worker - Bug 1492664
               TASKCLUSTER_ROOT_URL: https://taskcluster.net
               TASKCLUSTER_PROXY_URL: http://taskcluster
             - $if: 'tasks_for == "action"'
               then:
@@ -204,21 +203,19 @@ tasks:
                 --root=comm/taskcluster/ci
                 --pushlog-id='${push.pushlog_id}'
                 --pushdate='${push.pushdate}'
                 --project='${repository.project}'
                 --owner='${ownerEmail}'
                 --level='${repository.level}'
                 --base-repository="$GECKO_BASE_REPOSITORY"
                 --head-repository="$GECKO_HEAD_REPOSITORY"
-                --head-ref="$GECKO_HEAD_REF"
                 --head-rev="$GECKO_HEAD_REV"
                 --comm-base-repository="$COMM_BASE_REPOSITORY"
                 --comm-head-repository="$COMM_HEAD_REPOSITORY"
-                --comm-head-ref="$COMM_HEAD_REF"
                 --comm-head-rev="$COMM_HEAD_REV"
                 --try-task-config-file=comm/try_task_config.json
                 ${extraArgs}
 
         artifacts:
           'public':
             type: 'directory'
             path: '/builds/worker/artifacts'