$ git clone -n https://src.fedoraproject.org/rpms/rust-thiserror.git /var/lib/mock/f40-build-2259441-54370/root/chroot_tmpdir/scmroot/rust-thiserror
Cloning into '/var/lib/mock/f40-build-2259441-54370/root/chroot_tmpdir/scmroot/rust-thiserror'...
$ git fetch origin 0dbb1b1ef24306db85734e1a83ae8f09092c42d8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-thiserror
 * [new ref]         0dbb1b1ef24306db85734e1a83ae8f09092c42d8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0dbb1b1 Update to version 1.0.56; Fixes RHBZ#2256291