$ git clone -n https://github.com/xcp-ng-rpms/libtalloc /var/lib/mock/v8.3-incoming-10943-29394/root/chroot_tmpdir/scmroot/libtalloc
Cloning into '/var/lib/mock/v8.3-incoming-10943-29394/root/chroot_tmpdir/scmroot/libtalloc'...
$ git fetch origin e84ed24acab4c40f00339a4c6def58e24614dd7f:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libtalloc
 * [new ref]         e84ed24acab4c40f00339a4c6def58e24614dd7f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e84ed24 Import libtalloc-2.4.3-1.xs8.src.rpm