# HG changeset patch
# User Alexis S. L. Carvalho <alexis@cecm.usp.br>
# Date 1158169071 10800
# Node ID e7fc04dc6349cc171aba8c6cdeb4f2716386c440
# Parent  dc784839516d1104bb48282a87e4cc6c4adc9cf1
Avoid negative block sizes in lazyparser.

This fixes a bug introduced by changeset baa3873eb387 .

diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -143,7 +143,7 @@ class lazyparser(object):
                 # the revlog may have grown since we've started running,
                 # but we don't have space in self.index for more entries.
                 # limit blocksize so that we don't get too much data.
-                blocksize = self.datasize - blockstart
+                blocksize = max(self.datasize - blockstart, 0)
             data = self.dataf.read(blocksize)
         lend = len(data) / self.s
         i = blockstart / self.s