$ git clone -n https://src.fedoraproject.org/rpms/fedora-obsolete-packages.git /var/lib/mock/f40-build-1996282-43999/root/chroot_tmpdir/scmroot/fedora-obsolete-packages
Cloning into '/var/lib/mock/f40-build-1996282-43999/root/chroot_tmpdir/scmroot/fedora-obsolete-packages'...
$ git fetch origin c5af0f72122c9647e4c597bd76bade25b864695b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fedora-obsolete-packages
 * [new ref]         c5af0f72122c9647e4c597bd76bade25b864695b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c5af0f7 Obsolete R-rgdal