$ git clone -n https://src.fedoraproject.org/rpms/rust-num-bigint.git /var/lib/mock/f40-build-2038177-48157/root/chroot_tmpdir/scmroot/rust-num-bigint
Cloning into '/var/lib/mock/f40-build-2038177-48157/root/chroot_tmpdir/scmroot/rust-num-bigint'...
$ git fetch origin 4419933274b5c1c7dc93445b38b06308c5fbd58a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-num-bigint
 * [new ref]         4419933274b5c1c7dc93445b38b06308c5fbd58a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4419933 Update to version 0.4.4; Fixes RHBZ#2233687