$ git clone -n https://src.fedoraproject.org/rpms/perl-MIME-Base64.git /var/lib/mock/f45-build-24555-604/root/chroot_tmpdir/scmroot/perl-MIME-Base64
Cloning into '/var/lib/mock/f45-build-24555-604/root/chroot_tmpdir/scmroot/perl-MIME-Base64'...
$ git fetch origin f6c44bf95e1eeebb1f18e24b4dd3985eda5d552a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-MIME-Base64
 * [new ref]         f6c44bf95e1eeebb1f18e24b4dd3985eda5d552a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f6c44bf Increase release to favour standalone package