$ git clone -n https://src.fedoraproject.org/rpms/antlr4-project.git /var/lib/mock/f40-build-799084-142138/root/chroot_tmpdir/scmroot/antlr4-project
Cloning into '/var/lib/mock/f40-build-799084-142138/root/chroot_tmpdir/scmroot/antlr4-project'...
$ git fetch origin aa7061e60d52bdc9ed8754f8411f0f7df5acd8e0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/antlr4-project
 * [new ref]         aa7061e60d52bdc9ed8754f8411f0f7df5acd8e0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at aa7061e Add VCS field