contrib/python-hook-examples.py

largefiles: ensure lfutil.getstandinmatcher() only matches standins

Previously, simply having the largefiles extension loaded without any largefiles
added would crash when amending with -I.  The problem was with no files in the
matcher, the pattern list of files joined with 'standindir' was empty, and
scmutil.match() would match everything.  In lfutil.composestandinmatcher(), the
match function is used to test if the file is a standin, and after getting a
false positive, proceeds to call lfutil.splitstandin().  This returns None
because it isn't a standin, which blows up when passed to rmatcher.matchfn().

Manually overriding _always in getstandinmatcher() probably isn't necessary
anymore, but we leave well enough alone on stable.  This regressed in
ab618e52788a.

'''
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['tip'].node()
    else:
        last = node
    diff = patch.diff(repo, first, last)
    ui.write(patch.diffstat(util.iterlines(diff)))