contrib/python-hook-examples.py

packaging: add Provides: python3-mercurial and Homepage to debian package

There are other packages that depend on python3-mercurial, like debian's
mercurial-git, so we should mark ourselves as providing it.

I compared the control file we generate to the one that the debian maintainers
generate, and noticed several differences:
- the Homepage bit. I included this, because why not
- a more robust Suggests list that includes a graphical merge tool
- a more robust Breaks list
- debian's Recommends openssh-client, we only Recommends ca-certificates
- a split into `mercurial` and `mercurial-common` (and possibly others?)
- a slightly different description

Differential Revision: https://phab.mercurial-scm.org/D9983

'''
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)))