Fix pq.GlobalProperties test failure.

The test started failing after changes to active-server management in commit
10e6f51387a3f583957c497b73d009686b101feb. Since now it's possible to have a NULL
active session, we need to handle the case when there's no active proxy manager.

Change-Id: Ided651244ed83088a0d3d69f83a5e5a9dbd3e421
Fix Header test by excluding internal header.

Change-Id: I8e647dc45fbd97813e4d7327b0337716a2b35e2c
Merge topic 'refactor_python_interpretor' into next

96a5bbb Fix Header test by excluding internal header.
20d09ea Fix pq.GlobalProperties test failure.