BUG #16606: V 4.25: unable to drop database

The following bug has been logged on the website:

Bug reference:      16606
Logged by:          G. Borri
Email address:      g.borri@nemesix.it
PostgreSQL version: 10.14
Operating system:   ubuntu 18.04 desktop 64bit
Description:

Hi, after several attempts, I tried the system just started.
So I opened pgAdmin, insert my admin pwd, opened the server tree till the
database I need to delete.
Right click on the db name and then click on Delete/Drop database, then
click on OK on the confirm request. 
After some seconds this error appear: The database is in use, there is 1
session client.

Before the last update I was always able to delete the databases in this way