$ git clone -n https://src.fedoraproject.org/rpms/rust-thiserror-impl.git /var/lib/mock/f40-build-2260666-54417/root/chroot_tmpdir/scmroot/rust-thiserror-impl
Cloning into '/var/lib/mock/f40-build-2260666-54417/root/chroot_tmpdir/scmroot/rust-thiserror-impl'...
$ git fetch origin dd1e48550c873eacfc93f653baddf79d156c23e8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-thiserror-impl
 * [new ref]         dd1e48550c873eacfc93f653baddf79d156c23e8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dd1e485 Update to version 1.0.56; Fixes RHBZ#2256292