D3445: dispatch: shore up exit handling

[yuja (Yuya Nishihara)]

yuja added a comment.


  IIRC, SystemExit is caught at callcatch and translated to a status code.
  
  > +    # The logic here attempts to mimic how CPython's pythonrun.c does things.
  >  +    # Essentially:
  >  +    #
  >  +    # * Exit is controlled by returning a value or raising SystemExit.
  >  +    # * An integer value exits with that exit code.
  >  +    # * A value of ``None`` is interpreted as ``0``.
  >  +    # * A non-integer, non-None value results in that value being printed
  >  +    #   and an exit code of ``1``.
  >  +    # * SystemExit can have a ``code`` attribute containing the exit value.
  > 
  >   try:
  > 
  > - status = (dispatch(req) or 0) +        code = dispatch(req) or 0 except error.StdioError as e: err = e
  > - status = -1 +        code = -1 +    except SystemExit as err: +        try: +            code = err.code +            err = None +        except AttributeError:

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D3445

To: indygreg, #hg-reviewers
Cc: yuja, mercurial-devel