- make margin 10 sec more in 124a to let client kill some locks.

Rationale is the following:

* 30 sec we need because in 30 sec locks on client will get old enough to _start_ kiling them;
* 10 sec we need because client checks SLV and kills locks every 10 sec;
* 10 sec more we need to make sure that we did not race in worse case scenario and client really had some time to kill locks.