BUG #14798: postgres user superuser changed

The following bug has been logged on the website:

Bug reference: 14798
Logged by: Jenei Zsolt
Email address: jenei(dot)zsolt(at)dvs(dot)hu
PostgreSQL version: 9.4.1
Operating system: Windows 2012
Description:

Dear Support Colleagues,

we have a little team (3-4 people) developping commercial applications in
Hungary.
The client side has a Delphi 32bit Windows application. Yesterday was the
second time we expirienced that the superuser privilege of postgres user has
desappeared. Postgres user is the owner of all tables, so if we asked for
data as postgres, our application stopped working.
We have not changed anything on the entitlement system.
PostgreSQL is running on a server Windows 2012 which we do not operate. Is
it possible, that system administration has something to do with this
problem?
We were looking but have not found any log entry for this change.

Please let me know if something wasn’t clear above, and if you have any idea
what we can do with this problem.

Best regards,
Zsolt Jenei
Drén & Valner Szoftver Kft.