$ git clone -n https://src.fedoraproject.org/rpms/aerc.git /var/lib/mock/f40-build-796053-140458/root/chroot_tmpdir/scmroot/aerc
Cloning into '/var/lib/mock/f40-build-796053-140458/root/chroot_tmpdir/scmroot/aerc'...
$ git fetch origin 4b22604ae8d4afcc80125516604fd59b5bb1ee76:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/aerc
 * [new ref]         4b22604ae8d4afcc80125516604fd59b5bb1ee76 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4b22604 Sync LDFLAGS definition with upstream Makefile