$ git clone -n https://src.fedoraproject.org/rpms/regexp.git /var/lib/mock/f45-build-34435-686/root/chroot_tmpdir/scmroot/regexp
Cloning into '/var/lib/mock/f45-build-34435-686/root/chroot_tmpdir/scmroot/regexp'...
$ git fetch origin 46c4bfe1493122e2e7a846067e715c0908058e76:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/regexp
 * [new ref]         46c4bfe1493122e2e7a846067e715c0908058e76 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 46c4bfe Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild