$ git clone -n https://src.fedoraproject.org/rpms/rust-libcst.git /var/lib/mock/f42-build-3267411-41262/root/chroot_tmpdir/scmroot/rust-libcst
Cloning into '/var/lib/mock/f42-build-3267411-41262/root/chroot_tmpdir/scmroot/rust-libcst'...
$ git fetch origin abb7101c93336c152a13d0df0ed1c66ca0504df8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-libcst
 * [new ref]         abb7101c93336c152a13d0df0ed1c66ca0504df8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at abb7101 Update to version 1.6.0; Fixes RHBZ#2336766