$ git clone -n https://src.fedoraproject.org/rpms/xstream.git /var/lib/mock/f41-build-781168-13559/root/chroot_tmpdir/scmroot/xstream
Cloning into '/var/lib/mock/f41-build-781168-13559/root/chroot_tmpdir/scmroot/xstream'...
$ git fetch origin ad34885095cc0925fe213d53af2e5e27499fb86b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xstream
 * [new ref]         ad34885095cc0925fe213d53af2e5e27499fb86b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ad34885 Set Java version to 1.8