$ git clone -n https://src.fedoraproject.org/rpms/ninja-build.git /var/lib/mock/f43-build-61055735-6588266/root/chroot_tmpdir/scmroot/ninja-build
Cloning into '/var/lib/mock/f43-build-61055735-6588266/root/chroot_tmpdir/scmroot/ninja-build'...
$ git fetch origin 51e99f9ce4821b8dcb5a6e789bd341dd5ffca3a0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ninja-build
 * [new ref]         51e99f9ce4821b8dcb5a6e789bd341dd5ffca3a0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 51e99f9 Update to 1.13.1 (rhbz#2379488)