gh-135683: Ensure that WatchedFileHandler calls handleError on exceptions.

[vsajip]

• Issue: Log File Handlers Do not Respect logging.raiseExceptions = False #135683

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[picnixz]

Very silly but I wonder whether a possible AttributeErrorn raised when _open() is missing should be handled or not. Maybe we should only catch the exception when doing:

do_open = self._open
try:
    stream = do_open()
except Exception:
    self.handleError(record)
else:
    self._stream = stream

Or do you think it makes sense to let exceptions happening when setting the field and accessing _open() being handled normally?

[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[serhiy-storchaka]

Ah, oops — I did not notice this PR when I created the almost identical #154542. Well, at least this confirms the approach is correct.

One thing to note: #154542 does not call FileHandler.emit() if reopening failed. Otherwise the same error is handled twice.

[serhiy-storchaka]

Merged #154542 which is stricter and has @vsajip's approval. Added @vsajip as co-author.