Check for --google3 is not added as a flag when releasing

Bug: 143499693
Change-Id: Ib7c19537f84e344f88ac0f41c37c9df5c54240f7
diff --git a/tools/r8_release.py b/tools/r8_release.py
index 5e070ea..3575edf 100755
--- a/tools/r8_release.py
+++ b/tools/r8_release.py
@@ -369,6 +369,10 @@
     print "When releasing a release version add the list of bugs by using '--bug'"
     sys.exit(1)
 
+  if args.version and not 'dev' in args.version and args.google3:
+    print "You should not roll a release version into google 3"
+    sys.exit(1)
+
   return args