$ git clone -n https://src.fedoraproject.org/rpms/perl-Class-Std.git /var/lib/mock/f41-build-1250916-22988/root/chroot_tmpdir/scmroot/perl-Class-Std
Cloning into '/var/lib/mock/f41-build-1250916-22988/root/chroot_tmpdir/scmroot/perl-Class-Std'...
$ git fetch origin 2b039d69f5f3914b7e8a43f42d6fccd49c2c5ec4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Class-Std
 * [new ref]         2b039d69f5f3914b7e8a43f42d6fccd49c2c5ec4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2b039d6 Eliminate use of obsolete %patchN syntax (#2283636)