diff -r a708b65baeb9 -r ee112eb69d2a mercurial/revlog.py
--- a/mercurial/revlog.py	Tue Nov 01 15:37:00 2011 -0500
+++ b/mercurial/revlog.py	Thu Nov 03 11:24:55 2011 -0500
@@ -800,6 +800,7 @@
         readahead = max(65536, length)
         df.seek(offset)
         d = df.read(readahead)
+        df.close()
         self._addchunk(offset, d)
         if readahead > length:
             return d[:length]