Merge branch 'mysql-5.1' into mysql-5.5

sql/opt_range.cc

-/* Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights
+/* Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights
  * reserved.
 
    This program is free software; you can redistribute it and/or modify
@@ -3296,7 +3296,16 @@ int find_used_partitions(PART_PRUNE_PARAM *ppar, SEL_ARG *key_tree)
                                          key_tree->min_flag |
                                            key_tree->max_flag,
                                          &subpart_iter);
-      DBUG_ASSERT(res); /* We can't get "no satisfying subpartitions" */
+      if (res == 0)
+      {
+        /*
+           The only case where we can get "no satisfying subpartitions"
+           returned from the above call is when an error has occurred.
+        */
+        DBUG_ASSERT(range_par->thd->is_error());
+        return 0;
+      }
+
       if (res == -1)
         goto pop_and_go_right; /* all subpartitions satisfy */