Strip trailing spaces in pydoc

[serhiy-storchaka]

pydoc generates text output which can contain trailing spaces as a result of indentation of an empty line. It causes constant headashe in tests containing the pydoc output, because some editors automatically remove trailing spaces, and trailing spaces are usually difficult to notice. You need to replace trailing spaces with \x20, and do it every time you change the expected output, but since not all editors strip trailing spaces, you can introduce trailing spaces which will be stripped when somebody else edit that file, adding unrelated changes which break tests.

See for example 1a82f7e, but there were more recent examples, and test_enum currently contains trailing spaces.