contrib/python-hook-examples.py

tests: make test-worker.t pass on py2

I broke the py2 version in https://phab.mercurial-scm.org/D9287
because the `WorkerError.__bytes__()` (or `.__str__()`?) output was
different in py2 compared to py3. Part of the problem was that I
didn't propagate the status code that was passed in to the superclass
so it could get printed. This patch fixes that. I don't know how it
worked on py3 before this patch...

I also added the usual `__bytes__ = _tobytes` override for good
measure. It doesn't seem to be needed for tests to pass, though.

Differential Revision: https://phab.mercurial-scm.org/D9377

'''
Examples of useful python hooks for Mercurial.
'''
from __future__ import absolute_import
from mercurial import (
    patch,
    util,
)


def diffstat(ui, repo, **kwargs):
    '''Example usage:

    [hooks]
    commit.diffstat = python:/path/to/this/file.py:diffstat
    changegroup.diffstat = python:/path/to/this/file.py:diffstat
    '''
    if kwargs.get('parent2'):
        return
    node = kwargs['node']
    first = repo[node].p1().node()
    if 'url' in kwargs:
        last = repo.changelog.tip()
    else:
        last = node
    diff = patch.diff(repo, first, last)
    ui.write(patch.diffstat(util.iterlines(diff)))