While it's undocumented in the main docs [1], help(decimal.localcontext) in 3.2 starts with:

localcontext(ctx=None)
    Return a context manager for a copy of the supplied context

We essentially have two votes in favour of "it should work" (the pure Python impl and the docstring), and two in favour of "meh" (the prose docs and the lack of a test case)

I think we should fix it, but I don't mind if Georg wants it to wait until 3.3.1

[1] http://docs.python.org/py3k/library/decimal#decimal.localcontext