Gets the commit ID that the given annotated_commit
refs to.
Atomically increments the reference count of annotated_commit
by one.
This function is MT-safe and may be called from any thread.
Atomically decrements the reference count of annotated_commit
by one.
If the reference count drops to 0, annotated_commit
is freed.
Create a GgitAnnotatedCommit from the given reference
the repository
the reference to use to lookup the git_annotated_commit
Represents an annotated commit object.