$ git clone -n https://src.fedoraproject.org/rpms/perl-Sub-Prototype.git /var/lib/mock/f45-build-26433-617/root/chroot_tmpdir/scmroot/perl-Sub-Prototype
Cloning into '/var/lib/mock/f45-build-26433-617/root/chroot_tmpdir/scmroot/perl-Sub-Prototype'...
$ git fetch origin 4c514993fe968ce4cdf4ea5e7dfd8b5cba4472d6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Sub-Prototype
 * [new ref]         4c514993fe968ce4cdf4ea5e7dfd8b5cba4472d6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4c51499 Perl 5.44 rebuild