EoMPLS vlan rewrite between brands; possibly new bug in Cisco IOS 15

[Jonas Bjork <mr.jonas.bjork () me com>]

Hi, I am using a couple of AToM/EoMPLS tunnels in order to carry customer voice and data traffic across our IP/MPLS 
core, and it is currently working just fine. The first side consists of a Cisco 7600 router (rsp) and the other one is 
an HP A5500-HI routing switch with full LER/E-LSR capability. At the HP site, the tunnels are facing the access ports 
towards our premium end-customers; and on the Cisco PE I terminate the tunnels on one of the 2x10GE portchannel 
backbone links. There is vlan X on the HP side and vlan Y on the Cisco side - vlan rewrite is working perfectly - as 
long as I use IOS 12.

After upgrading the Cisco router software to IOS 15 the tunnels won't come up. sh mpls l2 vc Y d says:
...
Last error: Imposition VLAN rewrite capability mismatch with peer
...

I use almost exactly the same Cisco configuration before and after the upgrade (only minor changes and nothing related 
to this) and I havn't touched the HP. Apparently they don't talk the same L2PW language. I wonder though, why now? We 
use service instances on the HP switchport as endpoint, we initiate the targetted LDP session in addition to the 
pseudowire handshake from a sub interface MPLS crossconnect. There is no MTU mismatch; not here - not anywhere.

Anyone heard of this issue or experienced it?

Best regards,

Jonas Björk
SNE, Europe/Sweden (hope you guys will help me anyway:)