libgit2/libgit2 — pull request #1815 by nulltoken (2013-08-29 17:03:02+00:00)
Title: Ask the odbbackend if the object exists before overwriting it

Now that #1785 is merged, `git_odb_stream_finalize_write()` calculates the object id before invoking the odb backend.

This gives a chance to the backend to check if it already knows this object.