$ git clone -n https://src.fedoraproject.org/rpms/pepc.git /var/lib/mock/f42-build-side-1-3523528-46210/root/chroot_tmpdir/scmroot/pepc
Cloning into '/var/lib/mock/f42-build-side-1-3523528-46210/root/chroot_tmpdir/scmroot/pepc'...
$ git fetch origin aa418d58ac8c4b3fdca12bb3ab3a9820e07c0456:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/pepc
 * [new ref]         aa418d58ac8c4b3fdca12bb3ab3a9820e07c0456 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at aa418d5 Update to 1.5.25 (rhbz#2221323)