$ git clone -n https://src.fedoraproject.org/rpms/rust-anstream.git /var/lib/mock/f40-build-2568555-62223/root/chroot_tmpdir/scmroot/rust-anstream
Cloning into '/var/lib/mock/f40-build-2568555-62223/root/chroot_tmpdir/scmroot/rust-anstream'...
$ git fetch origin 34e9e42c2d0c9bbeef4c25d65e0473de96ded7c6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-anstream
 * [new ref]         34e9e42c2d0c9bbeef4c25d65e0473de96ded7c6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 34e9e42 Update to version 0.6.13; Fixes RHBZ#2266420