def patch(self):
        """Adjust OpenFOAM build for spack.
           Where needed, apply filter as an alternative to normal patching."""
        self.rename_source()
        add_extra_files(self, self.common, self.assets)

        # Avoid WM_PROJECT_INST_DIR for ThirdParty, site or jobControl.
        # Use openfoam-site.patch to handle jobControl, site.
        #
        # Filtering: bashrc,cshrc (using a patch is less flexible)
        edits = {
            'WM_THIRD_PARTY_DIR':
            r'$WM_PROJECT_DIR/ThirdParty #SPACK: No separate third-party',
            'WM_VERSION': str(self.version),  # consistency
            'FOAMY_HEX_MESH': '',  # This is horrible (unset variable?)
        }
        rewrite_environ_files(  # Adjust etc/bashrc and etc/cshrc
            edits,
            posix=join_path('etc', 'bashrc'),
            cshell=join_path('etc', 'cshrc'))