Whoops! Looks like something I added as a temporary hack during debugging, and then accidentially left in place. This explains why I had two places stripping quotation marks: this one and my own line 452. I guess I'd better remove lines 442 through 444. My code doesn't provide a replacement for line 444, though. That came from f249ee3ea9a2a6a4b479da3b34be29af5d1a0a63, which copied it from cpython, where it was added in http://hg.python.org/cpython/rev/846ba2972d7c. But that line can be safely removed, since `email.utils` will [remove quotes](http://hg.python.org/cpython/file/7a125913a375/Lib/email/utils.py#l234) and later on [add quotes without escaping existing ones](http://hg.python.org/cpython/file/7a125913a375/Lib/email/utils.py#l317). To play it safe, I'll include backslashes and quotation marks in my doctest.