After upgrading to 1.7.3 version of this plugin, new parameter showed up:

configure block level ( ) block on global level ( ) block on node level

Unfortunately none of the options is selected by default, so that all of our configured jobs simply do not block at all.

It would be nice to provide default value equivalent to behavior prior version 1.7.3.

Workaround is obviously to set some option for all broken jobs.