facebook/tornado — pull request #639 by greghaynes (2012-11-20 22:40:31+00:00)
Title: Allow 304 responses to send content-length header

Removed check for content-length = 0 in simple_httpclient.

304 response codes can send a content-length header even though they cannot send a body. Werkzeugs static middleware is one library that does this.