Summary:
Changelog: [internal]
`updateMountedFlag` needs to be called only when new revision will be mounted. In case a commit is throttled, this wasn't the case. Therefore, moving cancellation of commit so it happens before `updateMountedFlag`. We already cancel commits on that place so it should be safe.
Reviewed By: shergin
Differential Revision: D26049262
fbshipit-source-id: e0ecdd2d8f0cdb09d0c0a07ad3931ce77bcf03cf