R1:0d9ca2589f7c

Make sure `offset` is an integer

Summary:
Older git versions allowed the `--skip` to get empty string as value and interpreted that to an int.
We were sending `null` in some places where we wanted a `0`, so it all worked out.

Since https://git.kernel.org/pub/scm/git/git.git/commit/revision.c?id=71a1e94821666909b7b2bd62a36244c601f8430e git fails when provided empty string for an integer.

See Q124 and T15783.

Test Plan: Have recent git version (that fails with `--skip ''`, navigate to…