Add paranoia to diff code

mercurial/hg.py

@@ -78,7 +78,11 b' class manifest(revlog):'
     def diff(self, a, b):
         # this is sneaky, as we're not actually using a and b
         if self.listcache and len(self.listcache[0]) == len(a):
-            return mdiff.diff(self.listcache[1], self.addlist, 1)
+            d = mdiff.diff(self.listcache[1], self.addlist, 1)
+            if mdiff.patch(a, d) != b:
+                sys.stderr.write("*** sortdiff failed, falling back ***\n")
+                return mdiff.textdiff(a, b)
+            return d
         else:
             return mdiff.textdiff(a, b)
 

mercurial/revlog.py

@@ -190,7 +190,8 b' class revlog:'
 
         (p1, p2) = self.parents(node)
         if node != hash(text, p1, p2):
-            raise "integrity check failed on %s:%d" % (self.datafile, rev)
+            raise IOError("integrity check failed on %s:%d"
+                          % (self.datafile, rev))
 
         self.cache = (node, rev, text)
         return text  
@@ -210,7 +211,10 b' class revlog:'
             start = self.start(base)
             end = self.end(t)
             prev = self.revision(self.tip())
-            data = compress(self.diff(prev, text))
+            d = self.diff(prev, text)
+            if self.patches(prev, [d]) != text:
+                raise AssertionError("diff failed")
+            data = compress(d)
             dist = end - start + len(data)
 
         # full versions are inserted when the needed deltas