$ git clone -n https://src.fedoraproject.org/rpms/perl-B-Utils.git /var/lib/mock/f45-build-21851-588/root/chroot_tmpdir/scmroot/perl-B-Utils
Cloning into '/var/lib/mock/f45-build-21851-588/root/chroot_tmpdir/scmroot/perl-B-Utils'...
$ git fetch origin c5e6535c5bd1a0ce1a20cb0aa918e3829c6b9f39:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-B-Utils
 * [new ref]         c5e6535c5bd1a0ce1a20cb0aa918e3829c6b9f39 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c5e6535 Perl 5.44 rebuild