Fine-grained: Failure to propagate change of module to variable

[JukkaL]

This fine-grained incremental mode test case fails (it generates no errors after update):

[case testChangeModuleToVariable]
from a import m
m.x
[file a.py]
from b import m
[file b.py]
import m
[file b.py.2]
m = ''
[file m.py]
x = 1
[file m2.py]
[out]
==
main:2: error: "str" has no attribute "x"

Analysis: <a.m> doesn't get triggered when processing a. This is likely caused by not using symbol table snapshot comparison to detect changes in a when propagating changes. We correctly use snapshot comparison when processing a module source change but not when propagating changes using fine-grained dependencies.