facebook/tornado — pull request #393 by lerks (2011-10-29 22:24:23+00:00)
Title: Add Content-Length header on HEAD requests for StaticFileHandler

Normally Tornado would autocompute the Content-Length header based on the length of the message body. But in case of a HEAD request the message body is empty, thus the Content-Length header would have a value of zero. This is incorrect, since the headers in a HEAD request should be exactly the same as the equivalent GET request. This small patch fixes the bug.