$ git clone -n https://src.fedoraproject.org/rpms/perl-File-MMagic.git /var/lib/mock/f41-build-1153733-21307/root/chroot_tmpdir/scmroot/perl-File-MMagic
Cloning into '/var/lib/mock/f41-build-1153733-21307/root/chroot_tmpdir/scmroot/perl-File-MMagic'...
$ git fetch origin f473f9a9ab83e676be4fc5ceda28b642b69f23c9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-File-MMagic
 * [new ref]         f473f9a9ab83e676be4fc5ceda28b642b69f23c9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f473f9a Eliminate use of obsolete %patchN syntax (#2283636)