[PATCH 1 of 3 stable] obsolete: stop doing membership test on list

[pierre-yves.david at ens-lyon.org]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at ens-lyon.org>
# Date 1384652098 18000
#      Sat Nov 16 20:34:58 2013 -0500
# Branch stable
# Node ID 77ec457df3be5d413a14b31c02df2f51628396e2
# Parent  cb466830826a5fb0eecd4428922c2618d6a1b8af
obsolete: stop doing membership test on list

According to the Surgeon General, computer should not use list for membership
testing because of the risk of being slow.

diff --git a/mercurial/obsolete.py b/mercurial/obsolete.py
--- a/mercurial/obsolete.py
+++ b/mercurial/obsolete.py
@@ -265,11 +265,12 @@ class obsstore(object):
 
         Take care of filtering duplicate.
         Return the number of new marker."""
         if not _enabled:
             raise util.Abort('obsolete feature is not enabled on this repo')
-        new = [m for m in markers if m not in self._all]
+        known = set(self._all)
+        new = [m for m in markers if m not in known]
         if new:
             f = self.sopener('obsstore', 'ab')
             try:
                 # Whether the file's current position is at the begin or at
                 # the end after opening a file for appending is implementation