Index: trunk/ippTasks/diff.pro
===================================================================
--- trunk/ippTasks/diff.pro	(revision 26985)
+++ trunk/ippTasks/diff.pro	(revision 26987)
@@ -416,5 +416,9 @@
   task.exec
     if ($LABEL:n == 0) break
-    $run = difftool -revertdiffskyfile 
+    # Only revert failures with fault=2 (SYS_ERROR), which tend to be
+    # temporary filesystem problems.  Every other fault type is
+    # interesting and should be kept for debugging (and so it doesn't
+    # continue to occur).
+    $run = difftool -revertdiffskyfile -fault 2
     if ($DB:n == 0)
       option DEFAULT