Unable to union Resultsets using aliases

[Bernd Rössl]

The test

{{{
        result1 = self.store.find(Alias(Foo.title, 'title'))
        result2 = self.store.find(Alias(Bar.title, 'title'))
        result = result1.union(result2)
}}}

fails with the error

{{{
        FeatureError: Incompatible results for set operation
}}}

caused by the method FindSpec.is_compatible(find_spec) since `info1 is not info2`.
I do not see a reason why to check the 'info' in case of a union operation.

The easiest way to fix this error is to remove the check.

{{{
@@ -1696,8 +1696,6 @@ class FindSpec(object):
             self._cls_spec_info, find_spec._cls_spec_info):
             if is_expr1 != is_expr2:
                 return False
- if info1 is not info2:
- return False
         return True

     def load_objects(self, store, result, values)
}}}