cd6572d435
Under certain circumstances, when pushing to 'refs/changes/n', the same commit can be pushed onto multiple changes even if they are on the same branch. As a result of this, if the commit sha1 is used as change identifier in the 'review' ssh command, it will fail with the error: 'fatal: <SHA1> matches multiple patch sets.' This commit performs the same check as when pushing to 'refs/for/branch' to prevent this, and will show "commit already exists (in the project)" error message to reject uploading a commit to an existing change via `refs/changes/n` if the commit was already successfully pushed to a change in project scope. Bug: issue 2374 Change-Id: I1c000b2cc3e155617cdc9c295a46ce2107ec47ca