$ git clone -n https://src.fedoraproject.org/rpms/regexp.git /var/lib/mock/f40-build-2204950-51976/root/chroot_tmpdir/scmroot/regexp
Cloning into '/var/lib/mock/f40-build-2204950-51976/root/chroot_tmpdir/scmroot/regexp'...
$ git fetch origin 165ccb864b4e69a1234cd2ed3cfefafea508e1e0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/regexp
 * [new ref]         165ccb864b4e69a1234cd2ed3cfefafea508e1e0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 165ccb8 Update javapackages test plan to f40