[PATCH 02 of 12 V2] localrepo: introduce "prepushoutgoinghooks" to extend outgoing check easily

[FUJIWARA Katsunori]

# HG changeset patch
# User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
# Date 1397576244 -32400
#      Wed Apr 16 00:37:24 2014 +0900
# Node ID 5d2bfff9bd3381e8f2513fdd5cf1211de84a72b1
# Parent  12697af3f035c1a712edfcacf5e2e0d9324838d6
localrepo: introduce "prepushoutgoinghooks" to extend outgoing check easily

This patch introduces "prepushoutgoinghooks" to extend outgoing check
before pushing changesets to remote easily.

This chooses the function returning "util.hooks" instead of the one to
be overridden.

The latter may cause problems silently, if one of overriders forgets
(or fails) to execute a kind of "super(xxx, self).overridden(...)". In
the other hand, the former can ensure that all registered functions
are invoked, unless one of them raises an exception.

diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -103,6 +103,9 @@
         try:
             _pushdiscovery(pushop)
             if _pushcheckoutgoing(pushop):
+                pushop.repo.prepushoutgoinghooks(pushop.repo,
+                                                 pushop.remote,
+                                                 pushop.outgoing)
                 _pushchangeset(pushop)
             _pushcomputecommonheads(pushop)
             _pushsyncphase(pushop)
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1696,6 +1696,13 @@
         """
         pass
 
+    @unfilteredpropertycache
+    def prepushoutgoinghooks(self):
+        """Return util.hooks consists of "(repo, remote, outgoing)"
+        functions, which are called before pushing changesets.
+        """
+        return util.hooks()
+
     def push(self, remote, force=False, revs=None, newbranch=False):
         return exchange.push(self, remote, force, revs, newbranch)