register ignore_pip_unversioned_pkgs in config.py

Author: jfgrimm

easybuild/tools/config.py

@@ -376,6 +376,7 @@ def mk_full_default_path(name, prefix=DEFAULT_PREFIX):
     EMPTY_LIST: [
         'accept_eula_for',
         'from_pr',
+        'ignore_pip_unversioned_pkgs',
         'include_easyblocks_from_pr',
         'robot',
         'search_paths',