vim omnifunc Python is broken.

[samba]

Somehow Python fails to import the itertools module due to a code signature fault.

(Update: a more concise view, via vim -c "python import difflib")

The bulk of the interesting bits...

ImportError: dlopen(/usr/local/Cellar/python@2/2.7.15_1/Frameworks/Python.framework/Versions/2.7/lib/p
ython2.7/lib-dynload/itertools.so, 0x0002): code signature in (/usr/local/Cellar/python@2/2.7.15_1/Fra
meworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload/itertools.so) not valid for use in pro
cess: mapped file has no cdhash, completely unsigned? Code has to be at least ad-hoc signed.

Confirmed that the binary in use is provided by Homebrew:

:python import sys; print sys.executable
> /usr/local/opt/python@2/bin/python2.7