$ git clone -n https://src.fedoraproject.org/rpms/rust-idna0.2.git /var/lib/mock/f41-build-side-1-3098658-39333/root/chroot_tmpdir/scmroot/rust-idna0.2
Cloning into '/var/lib/mock/f41-build-side-1-3098658-39333/root/chroot_tmpdir/scmroot/rust-idna0.2'...
$ git fetch origin bd882107c4e5143c23ec1d24c8ceaab18ee7b04a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-idna0.2
 * [new ref]         bd882107c4e5143c23ec1d24c8ceaab18ee7b04a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at bd88210 compat package no longer needed