$ git clone -n https://src.fedoraproject.org/rpms/tcl-thread.git /var/lib/mock/f42-build-868770-176255/root/chroot_tmpdir/scmroot/tcl-thread
Cloning into '/var/lib/mock/f42-build-868770-176255/root/chroot_tmpdir/scmroot/tcl-thread'...
$ git fetch origin d630d72010d0d3ab730a2f1c2fc6a28ad2815580:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tcl-thread
 * [new ref]         d630d72010d0d3ab730a2f1c2fc6a28ad2815580 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d630d72 Fix BRs.