$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gdk_pixbuf2.git /var/lib/mock/f40-build-1780588-24818/root/chroot_tmpdir/scmroot/rubygem-gdk_pixbuf2
Cloning into '/var/lib/mock/f40-build-1780588-24818/root/chroot_tmpdir/scmroot/rubygem-gdk_pixbuf2'...
$ git fetch origin 4ff430b5684f3253b636a8b215c6ad6d4b01c5da:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gdk_pixbuf2
 * [new ref]         4ff430b5684f3253b636a8b215c6ad6d4b01c5da -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4ff430b 4.2.2 entry