Polari shows wrong port number in connection settings

[Marius Gedminas]

I'm connecting to my ZNC instance, reachable via an SSH tunnel through localhost:7777. If I open Polari's connection preferences, it shows me

   Server address: [ localhost:6697 ]

I can try to change it to localhost:7777, hit apply, close the dialog, and when I open it again, the port is, once again, shown incorrectly as 6697.

(If I check Online Accounts in System Preferences, I see that the port is actually 7777.)

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: polari 3.24.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.10.0-20.22-generic 4.10.8
Uname: Linux 4.10.0-20-generic x86_64
NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
ApportVersion: 2.20.4-0ubuntu4
Architecture: amd64
CurrentDesktop: GNOME
Date: Fri Apr 28 14:53:48 2017
InstallationDate: Installed on 2016-09-10 (230 days ago)
InstallationMedia: Ubuntu-GNOME 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160720)
SourcePackage: polari
UpgradeStatus: Upgraded to zesty on 2017-04-14 (14 days ago)