Remove master from dev release commit messages

Bug: 163417450
Change-Id: I5e7aaf3ca6fa90b8eb5a203673c204ffbc0ca249
diff --git a/tools/r8_release.py b/tools/r8_release.py
index 0612c36..3641f0c 100755
--- a/tools/r8_release.py
+++ b/tools/r8_release.py
@@ -210,7 +210,7 @@
 
     git_message = ("""Update D8 and R8 to %s
 
-Version: master %s
+Version: %s
 This build IS NOT suitable for preview or public release.
 
 Built here: go/r8-releases/raw/%s
@@ -249,7 +249,7 @@
   return release_maven
 
 def git_message_dev(version):
-  return """Update D8 R8 master to %s
+  return """Update D8 R8 to %s
 
 This is a development snapshot, it's fine to use for studio canary build, but
 not for BETA or release, for those we would need a release version of R8