Fix the import machinery if there is an error on sys.path or sys.meta_path
Fix the import machinery if there is an error on sys.path or sys.meta_path

find_module() now raises a RuntimeError, instead of ImportError, on an error on
sys.path or sys.meta_path because load_package() and import_submodule() returns
None and clear the exception if a ImportError occurred.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator