def METHOD_NAME(mutable_mock_env_path, monkeypatch):
    """Verify that stage filters specs in environment instead of reconcretizing."""
    def fake_stage(pkg, mirror_only=False):
        assert pkg.name == "mpileaks"
        assert pkg.version == Version("100.100")
    monkeypatch.setattr(spack.package_base.PackageBase, "do_stage", fake_stage)
    e = ev.create("test")
    e.add("mpileaks@=100.100")
    e.concretize()
    with e:
        stage("mpileaks")