better process_replay context print [pr] (tinygrad#8856)

* better process_replay context print [pr]

* test: revert push cast

* Revert "test: revert push cast"

This reverts commit 38a2aef.

Author: Qazalin

test/external/process_replay/process_replay.py

@@ -61,7 +61,8 @@ def diff(offset:int, name:str, fxn:Callable) -> None:
       continue
     # try recreate
     try:
-      with Context(**{k:v.value for k,v in args[-2].items() if k in ContextVar._cache and k != "DEBUG"}): good = fxn(*args[:-2])
+      ctx_vars = {k:v.value for k,v in args[-2].items() if k != "DEBUG" and (var:=ContextVar._cache.get(k)) is not None and var.value != v.value}
+      with Context(**ctx_vars): good = fxn(*args[:-2])
       if good is None: continue
     except Exception as e:
       changed += 1
@@ -72,7 +73,8 @@ def diff(offset:int, name:str, fxn:Callable) -> None:
     try: assert str(args[-1]) == str(good)
     except AssertionError:
       changed += 1
-      for x in args[:-1]: logging.info(x)
+      if ctx_vars: logging.info(ctx_vars)
+      for x in args[:-2]: logging.info(x)
       changes = list(difflib.unified_diff(str(good).splitlines(), str(args[-1]).splitlines()))
       logging.info("\n".join(colored(line, "red" if line.startswith("-") else "green" if line.startswith("+") else None) for line in changes))
       warnings.warn("PROCESS REPLAY DETECTED CHANGE", ProcessReplayWarning)