Using --ignore envokes E226 error

[mFoxRU]

Consider the following code:

print 1 + (2+3)

Running $ pep8 file.py gives no error. But adding --ignore= with any code gives:
file.py:1:14: E226 missing whitespace around arithmetic operator

[sigmavirus24]

By specifying your own ignore, you're overriding the DEFAULT_IGNORE that pep8 uses. This is expected (and, if I remember correctly, documented) behaviour.