$ git clone -n https://src.fedoraproject.org/rpms/centpkg.git /var/lib/mock/f42-build-side-1-3534248-46548/root/chroot_tmpdir/scmroot/centpkg
Cloning into '/var/lib/mock/f42-build-side-1-3534248-46548/root/chroot_tmpdir/scmroot/centpkg'...
$ git fetch origin 8d4002355d777452d7d401a1adb4ce83f7732fb0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/centpkg
 * [new ref]         8d4002355d777452d7d401a1adb4ce83f7732fb0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8d40023 Use authentication session for PP API