yapf --style=pep8 does not put spaces after a trailing comma

[DRMacIver]

Reformatting the following (pep8 correct) code:

trailing_comma = [
    1,
]

Results in the following:

trailing_comma = [1,]

PEP8 wants whitespace after the trailing comma. I can't immediately find a reference in PEP8 itself, but the pep8 checker program calls this E231.

[DRMacIver]

Confirmed in master.

[eliben]

This is the first time I hear that PEP8 requires whitespace after a trailing comma. The reformatting done by yapf seems reasonable here, and adding a space after the comma would be ugly.

Note that we have an algorithm in the works that will keep data structures with trailing commas as a one-per-line, so this specific issue will likely go away.