ha_innodb.cc, ha_innodb.h:

  Move to the right place the flag which bans use of HA_READ_PREFIX_LAST; add diagnostics and remove the assertion on line 2180 of ha_innodb.cc

sql/ha_innodb.cc

@@ -2179,7 +2179,12 @@ convert_search_mode_to_innobase(
 		case HA_READ_AFTER_KEY:		return(PAGE_CUR_G);
 		case HA_READ_BEFORE_KEY:	return(PAGE_CUR_L);
 		case HA_READ_PREFIX:		return(PAGE_CUR_GE);
-		case HA_READ_PREFIX_LAST:	ut_a(0); return(PAGE_CUR_LE);
+		case HA_READ_PREFIX_LAST:
+		        ut_print_timestamp(stderr);
+                        fprintf(stderr,
+			  " InnoDB: Warning: Using HA_READ_PREFIX_LAST\n");
+		        return(PAGE_CUR_LE);
+
 		        /* InnoDB does not yet support ..PREFIX_LAST!
 		        We have to add a new search flag
 		        PAGE_CUR_LE_OR_PREFIX to InnoDB. */

sql/ha_innodb.h

@@ -82,6 +82,7 @@ class ha_innobase: public handler
 			  HA_PRIMARY_KEY_IN_READ_INDEX |
 			  HA_DROP_BEFORE_CREATE |
 			  HA_NO_PREFIX_CHAR_KEYS |
+			  HA_NOT_READ_PREFIX_LAST |
 			  HA_TABLE_SCAN_ON_INDEX),
 	  last_dup_key((uint) -1),
 	  start_of_scan(0)
@@ -96,7 +97,7 @@ class ha_innobase: public handler
 	ulong index_flags(uint idx) const
 	{
 	  return (HA_READ_NEXT | HA_READ_PREV | HA_READ_ORDER |
-		  HA_KEY_READ_ONLY | HA_NOT_READ_PREFIX_LAST);
+		  HA_KEY_READ_ONLY);
 	}
   	uint max_record_length() const { return HA_MAX_REC_LENGTH; }
   	uint max_keys()          const { return MAX_KEY; }