[c-nsp] MPLS MTU [override] bug 12.4(22)T?

[Christopher Hunt]

I'm trying to configure "mpls mtu 1508" on a dot1q subinterface on a 
2851. IOS 12.4(7) will  allow it, but IOS 12.4(22)T won't.  The Bug 
Toolkit doesn't show any relevant bugs.  Has anyone else run into this?  
Is there a recommended release? I would really like a release that 
supports mpls tracroute.

router-1#sh ver
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 
12.4(7), RELEASE SOFTWARE (fc6)
...
ROM: System Bootstrap, Version 12.4(1r) [hqluong 1r], RELEASE SOFTWARE (fc1)
...
router-1 uptime is 53 minutes
System returned to ROM by reload at 14:42:21 PDT Thu Aug 6 2009
System image file is "flash:c2800nm-advipservicesk9-mz.124-7.bin"
...
Cisco 2851 (revision 53.51) with 509952K/14336K bytes of memory.
Processor board ID FTX...
16 FastEthernet interfaces
2 Gigabit Ethernet interfaces
1 Virtual Private Network (VPN) Module
DRAM configuration is 64 bits wide with parity enabled.
239K bytes of non-volatile configuration memory.
125440K bytes of ATA CompactFlash (Read/Write)

Configuration register is 0x2102

router-1#config term
Enter configuration commands, one per line.  End with CNTL/Z.
router-1(config)#int gi0/1.457  
router-1(config-subif)#mpls mtu ?
  <64-65535>  MTU (bytes)
router-1(config-subif)#mpls mtu 1508
router-1(config-subif)#end
router-1#sh run int gi0/1.457
...
interface GigabitEthernet0/1.457
 encapsulation dot1Q 457
 ip address x.x.x.x 255.255.255.252
 ip ospf network point-to-point
 no snmp trap link-status
 mpls ip
 mpls mtu 1508
 no cdp enable
end

!!!!

router-1#sh ver
Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 
12.4(22)T, RELEASE SOFTWARE (fc1)
...
router-1#conf term
Enter configuration commands, one per line.  End with CNTL/Z.
router-1(config)#int gi0/1.457
router-1(config-subif)#mpls mt
router-1(config-subif)#mpls mtu ?
  <64-1500>  MTU (bytes)
router-1(config-subif)#mpls mtu 1508
                                    ^
% Invalid input detected at '^' marker.

router-1(config-subif)#end
shelton-1#sh run int gi0/1.457
...
interface GigabitEthernet0/1.457
 encapsulation dot1Q 457
 ip address x.x.x.x 255.255.255.252
 ip ospf network point-to-point
 mpls mtu 1508
 mpls ip
 no cdp enable
end

-- 
cheers
Christopher Hunt