More detailed testing for value-error-too-few-values.

test/static_analysis/iterable.py

@@ -15,4 +15,7 @@ for x, y in dct:
 
 # Shouldn't cause issues, because if there are no types (or we don't know what
 # the types are, we should just ignore it.
+#! 0 value-error-too-few-values
 a, b = []
+#! 7 name-error
+a, b = NOT_DEFINED