$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gtksourceview2.git /var/lib/mock/f40-build-2205183-51988/root/chroot_tmpdir/scmroot/rubygem-gtksourceview2
Cloning into '/var/lib/mock/f40-build-2205183-51988/root/chroot_tmpdir/scmroot/rubygem-gtksourceview2'...
$ git fetch origin b90b46cf3b82022f9daae8e526d724249841046a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gtksourceview2
 * [new ref]         b90b46cf3b82022f9daae8e526d724249841046a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b90b46c SPDX migration