$ git clone -n https://src.fedoraproject.org/rpms/rust-thiserror.git /var/lib/mock/f40-build-1807591-24881/root/chroot_tmpdir/scmroot/rust-thiserror
Cloning into '/var/lib/mock/f40-build-1807591-24881/root/chroot_tmpdir/scmroot/rust-thiserror'...
$ git fetch origin 2edee0f9494105b24aae689d887efc7bd76abffb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-thiserror
 * [new ref]         2edee0f9494105b24aae689d887efc7bd76abffb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2edee0f Update to version 1.0.63; Fixes RHBZ#2297914