$ git clone -n https://src.fedoraproject.org/rpms/libXext.git /var/lib/mock/f40-build-784376-133362/root/chroot_tmpdir/scmroot/libXext
Cloning into '/var/lib/mock/f40-build-784376-133362/root/chroot_tmpdir/scmroot/libXext'...
$ git fetch origin 8985fcd6990818538325a79e8471525f4a62a679:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libXext
 * [new ref]         8985fcd6990818538325a79e8471525f4a62a679 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8985fcd libXext 1.3.6