$ git clone -n https://src.fedoraproject.org/rpms/perl-Goo-Canvas.git /var/lib/mock/f41-build-816708-150356/root/chroot_tmpdir/scmroot/perl-Goo-Canvas
Cloning into '/var/lib/mock/f41-build-816708-150356/root/chroot_tmpdir/scmroot/perl-Goo-Canvas'...
$ git fetch origin df683217304c98e96e8cc3687e6fd034a79e8ff5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Goo-Canvas
 * [new ref]         df683217304c98e96e8cc3687e6fd034a79e8ff5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at df68321 Perl 5.40 rebuild