These tests shows how SimpleHTTPRequestHandler behaves: if the class
contains a do_FOO method, it is called, otherwise error501 is raised.
That's what Karl said with «Or to modify the library code that for any
resources not yet defined.».
Since SimpleHTTPRequestHandler.do_HEAD exists, and this is reflected
in the correspondent unittest, I belive that this is not a bug.

Patch attached. No problem if it's not committed now. I hope that
someone in the noisy list will make a little cleanup one day :)

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> <http://bugs.python.org/issue13294>
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