$ git clone -n https://src.fedoraproject.org/rpms/rubygem-thor.git /var/lib/mock/f41-build-1197200-22336/root/chroot_tmpdir/scmroot/rubygem-thor
Cloning into '/var/lib/mock/f41-build-1197200-22336/root/chroot_tmpdir/scmroot/rubygem-thor'...
$ git fetch origin 2d05af29dda1fc3801308c5f41a58c0890aaa2d5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-thor
 * [new ref]         2d05af29dda1fc3801308c5f41a58c0890aaa2d5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2d05af2 Eliminate use of obsolete %patchN syntax (#2283636)