If an ancestry check of an annotated tag was triggered then the fetch from that peer would fail. This is due to graph_ahead_behind only working for commit-ish objects.

To allow for annotated tags, and other object that peel to commits, the check now peels the two objects to commits before getting their Oids. The call to graph_ahead_behind can take these two Oids instead.

A test for annotated tags is included as part of the examples/git suite in the CLI tests.

Rebase.