$ git clone -n https://src.fedoraproject.org/rpms/rust-clang-ast.git /var/lib/mock/f40-build-2640228-66393/root/chroot_tmpdir/scmroot/rust-clang-ast
Cloning into '/var/lib/mock/f40-build-2640228-66393/root/chroot_tmpdir/scmroot/rust-clang-ast'...
$ git fetch origin ad95dac6867d824b4738d9a55ae9e6602632e6eb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-clang-ast
 * [new ref]         ad95dac6867d824b4738d9a55ae9e6602632e6eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ad95dac Update to version 0.1.23 (rhbz#2269880)