[j-nsp] EX4200 virtual chassis problem, master going into linecard mode

[Victor Sudakov]

Dear Colleagues,

I've encountered an odd problem with adding EX4200s (running 12.3R6.6)
to Virtual Chassis with a nonprovisioned configuration file.

According to documentation, I zeroize the second switch, power it off,
connect to the running switch and power it on. Some magic happens, and
voila:

> show virtual-chassis

Virtual Chassis ID: 915f.3bb3.ff60
Virtual Chassis Mode: Enabled
                                           Mstr           Mixed Neighbor List
Member ID  Status   Serial No    Model     prio  Role      Mode ID  Interface
0 (FPC 0)  Prsnt    BM0213317561 ex4200-24t 128  Master*      N  1  vcp-0
1 (FPC 1)  Prsnt    BM0217040019 ex4200-24t 128  Backup       N  0  vcp-0

Member ID for next new member: 2 (FPC 2)

Looks fine, doesn't it? However, if I later poweroff the Backup switch
(BM0217040019), the current Master switch (BM0213317561) goes into linecard (sic!)
mode! And I lose ssh access to it. I can undo the disaster only from the
serial console.

What am I doing wrong? Or if it's a bug, is there a workaround?

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
AS43859