$ git clone -n https://src.fedoraproject.org/rpms/perl-String-Base.git /var/lib/mock/f41-build-816516-150225/root/chroot_tmpdir/scmroot/perl-String-Base
Cloning into '/var/lib/mock/f41-build-816516-150225/root/chroot_tmpdir/scmroot/perl-String-Base'...
$ git fetch origin 32b081919d9c27f50efb24ec88bd9ebd1b8578a8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-String-Base
 * [new ref]         32b081919d9c27f50efb24ec88bd9ebd1b8578a8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 32b0819 Perl 5.40 rebuild