$ git clone -n https://src.fedoraproject.org/rpms/Zim.git /var/lib/mock/f39-build-2175940-51072/root/chroot_tmpdir/scmroot/Zim
Cloning into '/var/lib/mock/f39-build-2175940-51072/root/chroot_tmpdir/scmroot/Zim'...
$ git fetch origin a17d9636b89d193b95d31acaae02d003093ec3a1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/Zim
 * [new ref]         a17d9636b89d193b95d31acaae02d003093ec3a1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a17d963 Avoid crash report when cancelling template copy (rhbz#2246676)