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.

Have recent git version (that fails with --skip '', navigate to /diffusion/1/history/master/) - see history.