contrib: add modern `setuptools` and `setuptools_scm` to the packaging venv With `py -3.9 contrib/packaging/packaging.py wix --pyoxidizer-target x86_64-pc-windows-msvc`, there is an immediate failure after building the venv (3.9.13 has `setuptools` 58.1.0): ModuleNotFoundError: No module named 'setuptools.command.build' With that fixed, the same command then fails immediately with this error: Couldn't import setuptools_scm (direct call of setup.py?) Unfortunately, referencing `setuptools` in the requirements file needs `--allow-unsafe` to avoid a warning about not pinning `setuptools`. However, the same warning happens if `setuptools` is pinned to a specific revision, so I have no idea what it is complaining about. It's a separate venv that is only used for packaging, so we can fix it if it becomes a problem in the future. Interestingly, the Inno installer build doesn't fail immediately, and I can see it installing `setuptools` and `setuptools_scm` in the wall of text it emits. Eventually it does fail with the same errors without this change.

'''
Examples of useful python hooks for Mercurial.
'''
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)))