$ git clone -n https://src.fedoraproject.org/rpms/rust-thiserror.git /var/lib/mock/f41-build-side-1-2897312-34638/root/chroot_tmpdir/scmroot/rust-thiserror
Cloning into '/var/lib/mock/f41-build-side-1-2897312-34638/root/chroot_tmpdir/scmroot/rust-thiserror'...
$ git fetch origin 87979f63a64adb38845e32b8f6756876565337b6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-thiserror
 * [new ref]         87979f63a64adb38845e32b8f6756876565337b6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 87979f6 Update to version 1.0.64; Fixes RHBZ#2314100