add comments to improve the diff parsing

Author: jakkdl

tests/autofix_files/async100.py

@@ -225,21 +225,24 @@ async def nursery_exit_blocks_with_start():
 async def autofix_multi_withitem():
     with open("foo"):  # error: 9, "trio", "CancelScope"
         ...
+
+    # this one is completely removed
     # error: 8, "trio", "CancelScope"
     # error: 8, "trio", "CancelScope"
     ...
 
+    # these keep the `open`
     with (
-        open("") as _,  # error: 8, "trio", "fail_after"
+        open("aa") as _,  # error: 8, "trio", "fail_after"
     ):
         ...
 
     with (
-        open("") as _,  # error: 8, "trio", "move_on_after"
+        open("bb") as _,  # error: 8, "trio", "move_on_after"
     ):
         ...
 
     with (
-        open("") as f,
+        open("cc") as f,
     ):
         ...

tests/autofix_files/async100.py.diff

@@ -189,41 +189,42 @@
 
 
  # async100 does not consider *redundant* cancel scopes
-@@ x,29 x,23 @@
+@@ x,32 x,26 @@
 
 
  async def autofix_multi_withitem():
 -    with trio.CancelScope(), open("foo"):  # error: 9, "trio", "CancelScope"
--        ...
 +    with open("foo"):  # error: 9, "trio", "CancelScope"
-+        ...
+         ...
+
+     # this one is completely removed
+-    with (
+-        trio.CancelScope(),  # error: 8, "trio", "CancelScope"
+-        trio.CancelScope(),  # error: 8, "trio", "CancelScope"
+-    ):
+-        ...
 +    # error: 8, "trio", "CancelScope"
 +    # error: 8, "trio", "CancelScope"
 +    ...
-+
-     with (
--        trio.CancelScope(),  # error: 8, "trio", "CancelScope"
--        trio.CancelScope(),  # error: 8, "trio", "CancelScope"
-+        open("") as _,  # error: 8, "trio", "fail_after"
-     ):
-         ...
 
+     # these keep the `open`
      with (
--        open("") as _,
+-        open("aa") as _,
 -        trio.fail_after(10),  # error: 8, "trio", "fail_after"
-+        open("") as _,  # error: 8, "trio", "move_on_after"
++        open("aa") as _,  # error: 8, "trio", "fail_after"
      ):
          ...
 
      with (
 -        trio.fail_after(5),  # error: 8, "trio", "fail_after"
--        open("") as _,
+-        open("bb") as _,
 -        trio.move_on_after(5),  # error: 8, "trio", "move_on_after"
--    ):
--        ...
--
--    with (
++        open("bb") as _,  # error: 8, "trio", "move_on_after"
+     ):
+         ...
+
+     with (
 -        trio.move_on_after(10),  # error: 8, "trio", "move_on_after"
-         open("") as f,
+         open("cc") as f,
      ):
          ...

tests/eval_files/async100.py

@@ -225,27 +225,30 @@ async def nursery_exit_blocks_with_start():
 async def autofix_multi_withitem():
     with trio.CancelScope(), open("foo"):  # error: 9, "trio", "CancelScope"
         ...
+
+    # this one is completely removed
     with (
         trio.CancelScope(),  # error: 8, "trio", "CancelScope"
         trio.CancelScope(),  # error: 8, "trio", "CancelScope"
     ):
         ...
 
+    # these keep the `open`
     with (
-        open("") as _,
+        open("aa") as _,
         trio.fail_after(10),  # error: 8, "trio", "fail_after"
     ):
         ...
 
     with (
         trio.fail_after(5),  # error: 8, "trio", "fail_after"
-        open("") as _,
+        open("bb") as _,
         trio.move_on_after(5),  # error: 8, "trio", "move_on_after"
     ):
         ...
 
     with (
         trio.move_on_after(10),  # error: 8, "trio", "move_on_after"
-        open("") as f,
+        open("cc") as f,
     ):
         ...