$ git clone -n https://src.fedoraproject.org/rpms/perl-Test-Deep.git /var/lib/mock/f42-build-side-1-3499879-45966/root/chroot_tmpdir/scmroot/perl-Test-Deep
Cloning into '/var/lib/mock/f42-build-side-1-3499879-45966/root/chroot_tmpdir/scmroot/perl-Test-Deep'...
$ git fetch origin eb5844d8ec46cba44ca489a77c9e7615f6956a9c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Test-Deep
 * [new ref]         eb5844d8ec46cba44ca489a77c9e7615f6956a9c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eb5844d Update to 1.205 (rhbz#2356679)