# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@logilab.fr>
# Date 2013-01-17 16:51:30
# Node ID 64848f7fb7642bd1554c97049cc08d049b02941c
# Parent  ecba9b0e767254c2b241657a9b591a2480f5811c

repoview: protect `base` computation from weird phase root

If for some reason the phase roots contains nullid, the set of filtered revs
will contains -1. That confuse Mercurial a lot. In particular this corrupt the
branchcache.

Standard code path does not result in nullid phase root. It can only result from
altered `.hg/store/phaseroots` or buggy extension. However better safe than
sorry.

diff --git a/mercurial/repoview.py b/mercurial/repoview.py
--- a/mercurial/repoview.py
+++ b/mercurial/repoview.py
@@ -90,6 +90,8 @@ def computeimpactable(repo):
     for roots in repo._phasecache.phaseroots[1:]:
         if roots:
             firstmutable = min(firstmutable, min(cl.rev(r) for r in roots))
+    # protect from nullrev root
+    firstmutable = max(0, firstmutable)
     return frozenset(xrange(firstmutable, len(cl)))
 
 # function to compute filtered set