Spurious E225 for some forms of tuple unpacking

[jek]

$ cat test
a, b = func(kw='k')
(a, b) = func(kw='k')
$ pep8 --repeat test 
test:2:17: E225 missing whitespace around operator

[florentx]

This error is because the test E225 does not see the opening parenthesis on first char.

This error is fixed on my branch. I fixed this one at the same time as issue #9.
It should be merged in trunk soon or later.