[Distutils] extends-cache

[Thomas Lotze]

Rafael Monnerat wrote:

> Feel free to review (and apply/branch if ok),

I've made some small adjustments and applied the patch to the zc.buildout
trunk.

> PS.: My english is not so good, so few free to improve my text on doctest
> :)

I rewrote most of the text to turn it more into documentation with
examples rather than a series of tests with some added comments. Also, the
patch to the download utility should actually not be necessary, that's
what logging is there for. Since I couldn't get logging to do what the
test needs at first try, I at least rewrote the patch to not rely on the
fallback option which is an implementation detail, and added a line that
removes the patch after the one test it was meant for.

Thank you for bringing up and fixing this issue!

-- 
Thomas