From: Srujith A Poojary <poojarysrujith@gmail.com>

The commit IDs shown in a submodule diff header belong to the
submodule's object database. However, strbuf_add_unique_abbrev()
uses the_repository, so it checks the superproject's object
database when abbreviating those IDs.

Use the submodule repository when it is available, and fall back
to the repository from the diff options when it is not.

Signed-off-by: Srujith A Poojary <poojarysrujith@gmail.com>

Submitted-As: https://lore.kernel.org/git/pull.2288.v2.git.1793473062113.gitgitgadget@gmail.com
In-Reply-To: https://lore.kernel.org/git/pull.2288.git.1793435149942.gitgitgadget@gmail.com