$ git clone -n https://src.fedoraproject.org/rpms/rust-calloop.git /var/lib/mock/f40-build-2650906-66878/root/chroot_tmpdir/scmroot/rust-calloop
Cloning into '/var/lib/mock/f40-build-2650906-66878/root/chroot_tmpdir/scmroot/rust-calloop'...
$ git fetch origin 0902af9f50a8acd842dabbf07c44b4a3050c6fa0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-calloop
 * [new ref]         0902af9f50a8acd842dabbf07c44b4a3050c6fa0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0902af9 Update to version 0.12.4; Fixes RHBZ#2258527