Title set by dbus method setTitle() should be sticky by default

It is not intuitive and easy for users to find they need also
call dbus method setTabTitleFormat() to avoid that title being
replaced on session activity.

BUG: 262089
FIXED-IN: 4.8

src/Session.cpp

@@ -1319,6 +1319,12 @@ void Session::setTitle(int role , const QString& title)
         break;
     case (1):
         this->setTitle(Session::DisplayedTitleRole, title);
+
+        // without these, that title will be overridden by the expansion of
+        // title format shortly after, which will confuses users.
+        _localTabTitleFormat = title;
+        _remoteTabTitleFormat = title;
+
         break;
     }
 }