Update forms.py to fix #284

[uy-rrodriguez]

An exception AttributeError is raised when child.targets[0] does not have an attribute name, as stated in the issue #284 .

meta.get_children() returns all children of the Meta class, which in the sample code contains a dictionary assignment.

The expected children are of type Assign whose first item in the attribute targets is of type AssignName, like AssignName.widgets(name='widgets').

An instruction like widget["field"] = forms.SomeWidget will result in a Assign child containing a Subscript(ctx=<Context.Store: 2>, value=<Name.widgets ...>, slice=<Index ...>). This is of course unexpected.

I guess other unexpected instructions in the Meta class can trigger similar errors, so probably the most economic solution is to enclose the code in try... except and ignore the AttributeError. Trying to identify the type of object before accessing the name attribute would probably incur in a slower execution.

[coveralls]

Pull Request Test Coverage Report for Build 1258

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 4 unchanged lines in 3 files lost coverage.
• Overall coverage decreased (-1.8%) to 86.867%

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Files with Coverage Reduction	New Missed Lines	%
pylint_django/augmentations/init.py	1	88.61%
pylint_django/checkers/forms.py	1	85.71%
pylint_django/checkers/django_installed.py	2	71.43%

Totals
Change from base Build 1183:	-1.8%
Covered Lines:	721
Relevant Lines:	830

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💛 - Coveralls

[asottile]

[uy-rrodriguez]

This seems cleaner than adding the isinstance before checking for the name, but it may need to be changed if at some point more verification is added to the children and you need to handle other types of items in targets.