Fix start of history manager from gajim

gajim/app_actions.py

@@ -63,15 +63,8 @@ class AppActions():
             interface.instances['accounts'] = config.AccountsWindow()
 
     def on_history_manager(self, action, param):
-        config_path = '-c %s' % gajim.gajimpaths.data_root
-        posix = os.name != 'nt'
-        if os.path.exists('history_manager.exe'):  # Windows
-            helpers.exec_command('history_manager.exe %s' % config_path,
-                                 posix=posix)
-        else:  # Linux or running from Git
-            helpers.exec_command(
-                '%s history_manager.py %s' % (sys.executable, config_path),
-                posix=posix)
+        from gajim.history_manager import HistoryManager
+        HistoryManager()
 
     def on_manage_bookmarks(self, action, param):
         config.ManageBookmarksWindow()