This condition happens when a user makes a second commit and tries to
replace it onto an existing change, e.g. if they did:
$ git commit
$ repo upload
... some time later ...
$ git commit
$ repo upload --replace .
... specify the prior change ...
Gerrit sees that the change depends upon itself, as the latest patch set
has an ancestor that is a prior patch set of the same change. This is a
very simple case to detect and error out on during upload, ensuring that
the user has an opportunity to correct their usage.
Bug: GERRIT-137
Signed-off-by: Shawn O. Pearce <sop@google.com>
a186fc5c53