This change allows (presumably accidental) whitespace to exist in multi-line basic strings between a line-ending backslash and the following newline. See #436 for more context.

@BurntSushi @ChristianSI Any feedback on this one?

LGTM.

I'm a bit troubled by the comment "(even though it will create an otherwise invalid backslash-space or backslash-tab)" for that reason that, if there is no accidental whitespace, the backslash followed by a linebreak it not a valid backslash escape sequence either. Hence I would prefer to delete that comment, as I found it needlessly confusing.

Looks good otherwise.

Also, I'd propose deleting the word "Accidental" since how is the parser to distinguish between "accidental whitespace" and "non-accidental whitespace"? (The current proposal, when read literally, prohibits the latter.)

There is presumably little reason to add whitespace in that position on purpose, but whether it was added on purpose or by accident is not for the spec writers to judge.

@ChristianSi Ok, try that wording on for size, I think it's much better.

@mojombo Excellent!