docs: disclose that the ast.unparse rewrite changes the compiled bytecode on 1 of 383 rows (src/00117.py, MBPP task_id 757) — co_code identical on all 383, set remains sound since reference and .pyc come from the same normalised string

README.md

@@ -98,6 +98,21 @@ Each reference solution was rewritten through `ast.unparse` — normalising away
 comments and redundant parentheses — then compiled to a `.pyc` at `optimize=0` and paired with a
 disassembly of the resulting code object. Task text and tests are unmodified.
 
+**That rewrite changes the compiled bytecode on 1 of the 383 rows.** CPython 3.12 inlines
+comprehensions (PEP 709) and emits a cleanup entry in the exception table for the inlined scope;
+how the comprehension is *line-wrapped* changes that entry. In `src/00117.py` (MBPP `task_id`
+757) the original solution wraps a nested comprehension across lines, so its bytecode differs
+from the normalised form shipped here. The instruction stream `co_code` is identical on all 383
+rows; this row differs only in that exception-table entry.
+
+The row is a valid decompilation task and the benchmark remains sound: for all 383 rows the
+reference source and the `.pyc` are compiled from **the same** normalised string, which is the
+condition the oracle needs. What the row is not is byte-identical to upstream MBPP — hence this
+note. Re-deriving it from the original would put that solution's tab continuations and trailing
+whitespace into the reference and make the label an unstable target, so it is documented instead.
+Measured with `tools/measure_format_ceiling.py`; the general limit is in
+`../../EVAL.md` §6.
+
 ## Harness soundness on this set
 
 `grade.py --self-test-only`: pre-flight **383/383 = 100%**, mutation kill rate **199/199 = 100%**,