[PATCH 19 of 22 V2-Series-D] hgweb: walk the graph through the changelog

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at ens-lyon.org>
# Date 1358109817 -3600
# Node ID e7888fbf2a7d88d9674d392f36575b67ca9ef5ea
# Parent  817010c2783b37b8851c1840f252db5b27f9167f
hgweb: walk the graph through the changelog

This is necessary to enforce filtering. The result is a bit buggy (may provide
less changeset than expected, but it will stop crashing on filtered revision
access.

Note that changelog.revs can not represents empty iteration like xrange did. So
we have to explicitly prevent call when there is nothing to do.

diff --git a/mercurial/hgweb/webcommands.py b/mercurial/hgweb/webcommands.py
--- a/mercurial/hgweb/webcommands.py
+++ b/mercurial/hgweb/webcommands.py
@@ -856,12 +856,15 @@ def graph(web, req, tmpl):
 
     uprev = min(max(0, count - 1), rev + revcount)
     downrev = max(0, rev - revcount)
     changenav = webutil.revnav(web.repo).gen(pos, revcount, count)
 
-    dag = graphmod.dagwalker(web.repo, range(start, end)[::-1])
-    tree = list(graphmod.colored(dag, web.repo))
+    tree = []
+    if start < end:
+        revs = list(web.repo.changelog.revs(end - 1, start))
+        dag = graphmod.dagwalker(web.repo, revs)
+        tree = list(graphmod.colored(dag, web.repo))
 
     def getcolumns(tree):
         cols = 0
         for (id, type, ctx, vtx, edges) in tree:
             if type != graphmod.CHANGESET: