[POOL_UPGRADE] Command doesn't work

Build Info:
sovrin-node 0.3.132 (Shakedown pool 3)

Overview:
Command doesn't work and breaks execution of following send NYM commands.

Preconditions:
Pool with not latest version.

Steps to Reproduce:
0. [Reproduce on Shakedown pool 3 only.]
1. Send POOL_UPGRADE command with valid parameters.
2. Send NYM command with valid paramteters.

Actual Results:
There is no success/error message for send POOL_UPGRADE.
There is no success/error message for send NYM.

Expected Results:
Both commands should work correctly.

Workaround:
Send NYM command start working after restarting all nodes (but send POOL_UPGRADE don't).