contrib/python-hook-examples.py

bundle2: fix raising errors during heads checking

If the heads on the server differ from the ones reported seen by the client at
bundle time, we raise a PushRaced exception. However, the part raising the
exception was broken.

To fix it, we move the PushRaced class in the error module so it can be
accessible everywhere without an import cycle.

A test is also added to prevent regression.

'''
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)))