$ git clone -n https://src.fedoraproject.org/rpms/libXcomposite.git /var/lib/mock/f40-build-2228193-53069/root/chroot_tmpdir/scmroot/libXcomposite
Cloning into '/var/lib/mock/f40-build-2228193-53069/root/chroot_tmpdir/scmroot/libXcomposite'...
$ git fetch origin 04208935a59ef4fffd4aa3bf14a86f634af6d36e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libXcomposite
 * [new ref]         04208935a59ef4fffd4aa3bf14a86f634af6d36e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0420893 libXcomposite 0.4.6