Fix bogus master-manager got_revision_mapping

Bug: 713356
TBR=tandrii@chromium.org

Change-Id: I4af86f67216e1fc07da099e42608ad4a93c6b354
Reviewed-on: https://chromium-review.googlesource.com/484401
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>

recipes/recipe_modules/gclient/config.py

@@ -552,6 +552,7 @@ def infradata_master_manager(c):
   soln.name = 'infra-data-master-manager'
   soln.url = (
       'https://chrome-internal.googlesource.com/infradata/master-manager.git')
+  del c.got_revision_mapping['infra_internal']
   c.got_revision_mapping['infra-data-master-manager'] = 'got_revision'
 
 @config_ctx()