--- a/tracext/hg/backend.py	Sun Jun 10 00:36:16 2012 +0200
+++ b/tracext/hg/backend.py	Sun Jun 10 22:41:07 2012 +0200
@@ -15,6 +15,7 @@
 
 from bisect import bisect
 from datetime import datetime
+from heapq import heappop, heappush
 import os
 import time
 import posixpath
@@ -941,8 +942,15 @@
         str_dirctxs = {}
         repo = self.repos.repo
         max_ctx = repo[max_rev]
-        for r in xrange(max_rev, -1, -1):
+        orevs = [-max_rev]
+        revs = set(orevs)
+        while orevs:
+            r = -heappop(orevs)
             ctx = repo[r]
+            for p in ctx.parents():
+                if p and p.rev() not in revs:
+                    revs.add(p.rev())
+                    heappush(orevs, -p.rev())
             # lookup changes to str_dirnames in current cset
             for str_file in ctx.files():
                 for str_dir in str_dirnames[:]:
@@ -972,10 +980,7 @@
                     str_files = str_entries[str_dir]
                     dr = str_dirctxs.get(str_dir, 0)
                     for f in str_files[:k]:
-                        try:
-                            dr = max(dr, max_ctx.filectx(f).linkrev())
-                        except LookupError:
-                            pass # that file was not on this revision `r`
+                        dr = max(dr, max_ctx.filectx(f).linkrev())
                     str_files = str_files[k:]
                     if str_files:
                         # not all files for str_dir seen yet,