Add missing closing parenthesis in expression

Initially missed because test was expected to fail, just not in
_this_ particular way...

tests/search/parent_child/imported_fields_in_selections.rb

@@ -293,7 +293,7 @@ def test_imported_fields_can_be_used_in_batch_remove_selections
     assert_equal([], enumerate_docs_matching(remove_cond))
     # Nothing else should be removed...!
     assert_equal(['id:test:child::1', 'id:test:child::2', 'id:test:child::5'],
-                 enumerate_docs_matching("not (#{remove_cond}"))
+                 enumerate_docs_matching("not (#{remove_cond})"))
   end
 
 end