E1133 False positive after isinstance(data, list)

[Gloweye]

Steps to reproduce

def queue(data):
    if data is None:
        data = {"pageSize": 100}
    for key, value in data.items():
        if isinstance(value, list):
            for val in value:
                print(val)

Current behavior

scratches\scratch_14.py:6:23: E1133: Non-iterable value value is used in an iterating context (not-an-iterable)

Expected behavior

Not getting this message after any isinstance(name, list) check, regardless of the data shape before that check.

pylint --version output

pylint 2.1.1
astroid 2.0.4
Python 3.6.3 |Anaconda custom (64-bit)| (default, Oct 15 2017, 03:27:45) [MSC v.1900 64 bit (AMD64)]

There's some weird-ass stuff going on here. For example, replacing that key, value in data.items() with a value in data.values() stops this false positive. Of course, the original problem was quite a bit bigger, and I actually use that key. Removing the if self.data is None check+result will remove the warning.

[PCManticore]

Duplicate of #1162. This is a long known problem of pylint as it currently cannot understand control flow primitives. This is somewhat on our roadmap, but not sure when it's going to be implemented per se, but you can check other similar issues https://github.com/PyCQA/pylint/issues?q=is%3Aissue+is%3Aopen+control+flow+label%3Atopic-control-flow.

[Gloweye]

Even if I'd seen the other one, I probably wouldn't have thought it a dupe. But ok, I'll just add a disable=E1133 to the block.