$ git clone -n https://src.fedoraproject.org/rpms/rust-regex.git /var/lib/mock/f40-build-2269365-54765/root/chroot_tmpdir/scmroot/rust-regex
Cloning into '/var/lib/mock/f40-build-2269365-54765/root/chroot_tmpdir/scmroot/rust-regex'...
$ git fetch origin e7fe7a8443805e544911df33c271e66db9a06001:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-regex
 * [new ref]         e7fe7a8443805e544911df33c271e66db9a06001 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e7fe7a8 Update to version 1.10.2; Fixes RHBZ#2244494