contrib/python-hook-examples.py

destroyed: invalidate phraserevs cache in all case (issue3858)

When revisions are destroyed, the `phaserevs` cache becomes invalid in most case.
This cache hold a `{rev => phase}` mapping and revision number most likely
changed.

Since 1c8e0d6ac3b0, we filter unknown phases' roots after changesets
destruction.  When some roots are filtered the `phaserevs` cache is invalidated.
But not if none root where destroyed.

We now invalidate the cache in all case filtered root or not.

This bug was a bit tricky to reproduce as in most case we either:
* rebase a set a draft changeset including root (phaserev invalidated)
* strip tip-most changesets (no re-numbering of revision)

Note that the invalidation of `phaserevs` are not strictly needed when only
tip-most part of the history have been destroyed. But I do not expect the
overhead to be significant.

'''
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)))