$ git clone -n https://src.fedoraproject.org/rpms/gstreamer1-plugins-base.git /var/lib/mock/f40-build-787467-134776/root/chroot_tmpdir/scmroot/gstreamer1-plugins-base
Cloning into '/var/lib/mock/f40-build-787467-134776/root/chroot_tmpdir/scmroot/gstreamer1-plugins-base'...
$ git fetch origin 2789ca25d4ef7516b2fd57e176571c24e7b59667:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gstreamer1-plugins-base
 * [new ref]         2789ca25d4ef7516b2fd57e176571c24e7b59667 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2789ca2 1.22.9