'Go to Definition' for relative imports not resolving directly to the appropriate module

[brettcannon]

Let's say I have pkg and pkg.subpkg, both packages. I also have pkg.mod and pkg.subpkg.submod, both modules. If I do from .. import mod from within pkg.subpkg.submode I get asked which package to resolve to -- pkg/__init__.py or pkg/mod.py -- even though pkg.__init__ is empty. I would expect the lack of ambiguity to not ask me which package to resolve to.

Attached are the test files I was using.
pkg.zip

[MikhailArkhipov]

To verify with #546