add bracket check in split_line (#1315)

black.py

@@ -2544,6 +2544,7 @@ def init_st(ST: Type[StringTransformer]) -> StringTransformer:
             is_line_short_enough(line, line_length=line_length, line_str=line_str)
             or line.contains_unsplittable_type_ignore()
         )
+        and not (line.contains_standalone_comments() and line.inside_brackets)
     ):
         # Only apply basic string preprocessing, since lines shouldn't be split here.
         transformers = [string_merge, string_paren_strip]

tests/data/comments.py

@@ -22,6 +22,11 @@
 
 
 # Some comment before a function.
+y = 1
+(
+    # some strings
+    y  # type: ignore
+)
 
 
 def function(default=None):