fix: replace bare except clauses with specific exception types (#3164)

[paulxg12]

Closes #3164 — replaces bare except: clauses in multicore_utils.py with specific exception types.

Changes in metaflow/multicore_utils.py:

• Line 25: except: → except ImportError: (py2/py3 cPickle compat pattern)
• Line 69: except: → except Exception: (child process error handler should allow SystemExit/KeyboardInterrupt to propagate to os._exit())

[greptile-apps]

Greptile Summary

This PR replaces two bare except: clauses in metaflow/multicore_utils.py with specific exception types, improving Python exception-handling hygiene.

• Line 25: except: → except ImportError: for the cPickle/pickle import fallback — the correct and narrowest exception type for a missing module.
• Line 69: except: → except Exception: in the forked child-process handler — SystemExit and KeyboardInterrupt (both BaseException subclasses, not Exception) now bypass the except clause; however, the finally block unconditionally calls os._exit(), so the child process still terminates cleanly regardless. The only behavioural difference is that tracebacks for those two signals will no longer be printed.

Confidence Score: 5/5

Safe to merge — both changes narrow bare except: clauses to the appropriate exception types without altering the function's core invariant.

The except ImportError: change is strictly correct for a module-import fallback. The except Exception: change in the forked child is also correct: KeyboardInterrupt/SystemExit now bypass the except clause, but the finally block still calls os._exit() unconditionally, so the child process always terminates. The only observable difference is that tracebacks for those two signals are no longer printed in the child, which is actually the more appropriate behaviour in a forked subprocess.

No files require special attention.

Important Files Changed

Filename	Overview
metaflow/multicore_utils.py	Two bare except: clauses replaced with except ImportError: and except Exception:; both changes are correct and the finally/os._exit() invariant is preserved.

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