$ git clone -n https://src.fedoraproject.org/rpms/R-profmem.git /var/lib/mock/f42-build-side-1-3501688-45976/root/chroot_tmpdir/scmroot/R-profmem
Cloning into '/var/lib/mock/f42-build-side-1-3501688-45976/root/chroot_tmpdir/scmroot/R-profmem'...
$ git fetch origin 7b07654648939c9411aa2f6e009bca106ddde82b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-profmem
 * [new ref]         7b07654648939c9411aa2f6e009bca106ddde82b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7b07654 R-maint-sig mass rebuild