rhg: refactor to pass argv down, instead of caling args_os() This refactoring makes it easy to patch some command-line preprocessing into rhg. We use this to support using rhg as a shebang interpreter, for example. Differential Revision: https://phab.mercurial-scm.org/D12543

narrow: support debugupgraderepo Differential Revision: https://phab.mercurial-scm.org/D12542

procutil: avoid `+= None` when writing to full std{err,out} descriptor on py3 The write function returns `None` if there was no room to write the given data[1]. I don't like that this is effectively an infinite loop if there's never any progress emptying the underlying buffer, but we're no worse off than before, and it fixes random stacktrace popups seen in the py3 build of TortoiseHg. [1] https://docs.python.org/3/library/io.html#io.RawIOBase.write Differential Revision: https://phab.mercurial-scm.org/D12555