$ git clone -n https://src.fedoraproject.org/rpms/freefem++.git /var/lib/mock/f42-build-864649-172514/root/chroot_tmpdir/scmroot/freefem++
Cloning into '/var/lib/mock/f42-build-864649-172514/root/chroot_tmpdir/scmroot/freefem++'...
$ git fetch origin 49287a4a527386d687e46d5188e6b8b8a1300f13:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/freefem++
 * [new ref]         49287a4a527386d687e46d5188e6b8b8a1300f13 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49287a4 Update to 4.15.