Query cancel seems to be broken in master since Oct 17

Hi,

In pgjdbc we have regular regression testing against "build from master" PostgreSQL, and recent master builds fail for "statement cancel" test.

The PostgreSQL as of Mon Oct 17 00:09:39 UTC 2016 was fine, then "statement cancel" started to fail.

The test executes "select pg_sleep(10)" and tries to cancel it. In recent master builds, cancel seems to be ignored, and the statement lasts for 10 seconds.

Exactly the same driver and test version works fine for 8.4, 9.1, 9.2, 9.3, 9.4, 9.5, and 9.6:

Here's a sample build report: https://travis-ci.org/pgjdbc/pgjdbc/builds/168444341 

Any hints what could be the issue?

Was the breakage intentional?

Vladimir