$ git clone -n https://src.fedoraproject.org/rpms/libbase.git /var/lib/mock/f41-build-1028884-18369/root/chroot_tmpdir/scmroot/libbase
Cloning into '/var/lib/mock/f41-build-1028884-18369/root/chroot_tmpdir/scmroot/libbase'...
$ git fetch origin 5a3fa94c04a41330a8a03492d875c7cefc3d9b19:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libbase
 * [new ref]         5a3fa94c04a41330a8a03492d875c7cefc3d9b19 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5a3fa94 Eliminate use of obsolete %patchN syntax (#2283636)