$ git clone -n https://src.fedoraproject.org/rpms/rubygem-cairo-gobject.git /var/lib/mock/f40-build-794372-139514/root/chroot_tmpdir/scmroot/rubygem-cairo-gobject
Cloning into '/var/lib/mock/f40-build-794372-139514/root/chroot_tmpdir/scmroot/rubygem-cairo-gobject'...
$ git fetch origin 437f80869ad11787dccf00bc57113d71e811e7e2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-cairo-gobject
 * [new ref]         437f80869ad11787dccf00bc57113d71e811e7e2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 437f808 4.2.1 entry