Restore the ability to use inline comments in config files

[neilmayhew]

This change is 

[JoeLametta]

Hi, one clarification: you titled "restore" but when did we drop the ability to use inline comments? (in which commit?).

[neilmayhew]

I added more info in the commit message, and also updated README.md. The exact commit where the ability was lost was 64dd9d8 but I'm not sure this is important to include in the commit message.

[JoeLametta]

Here I see this:

(For backwards compatibility, only ; starts an inline comment, while # does not.)

Also keep in mind that inline comments may cause interpolation errors. Example here: #443 (comment).

Um, don't know if restoring this would be a good idea...

[neilmayhew]

I suspect that #443 is actually a result of the problem this PR is trying to fix, because the comments won't have been treated as comments in any Python 3 version of whipper: they'll just have been part of the value. In other words, re-enabling inline comments would prevent that problem.

Without this PR, inline comments won't be possible at all, but they're used liberally in whipper's documentation and examples, so those places would all need to be updated.

However, more importantly, I expect many people (like me) have existing config files with comments in them that were used with a Python 2 version of whipper, and now whipper dies with a strange error message about boolean values whenever they try to run it.

[neilmayhew]

I'm not sure what you meant by the quote from the Python 2 documentation. That if we do re-enable comments we should allow only ; and not #?

[JoeLametta]

Hi, after some tests I've verified that:

1. before the Python 3 port occurred whipper used to recognize inline comments starting with character ; but not the ones with character #. This seems to be confirmed here too †
2. right now whipper allows no inline comments

I agree this is a regression so I'm going to merge this pull request but first I need you to edit it to remove character # as allowed inline comment prefix.

Cheers,
Joe

†

Changed in version 3.2: In previous versions of configparser behaviour matched
comment_prefixes=('#',';') and inline_comment_prefixes=(';',).

[neilmayhew]

Yes, I agree it's best to match the original behaviour exactly. Done.

[JoeLametta]

Merged, thanks!