diff --git a/src/command_system/mapping.py b/src/command_system/mapping.py
index fb8c83af8..707866a20 100644
--- a/src/command_system/mapping.py
+++ b/src/command_system/mapping.py
@@ -270,6 +270,16 @@ def adapt_arguments(command, arguments, args, opts):
             if value not in initial:
                 raise CommandError("%s: Invalid argument" % key, command)
 
+    # If argument to an option constrained by a sequence was not given - then
+    # it's value should be set to None.
+    for spec_key, spec_value in spec_kwargs:
+        if isinstance(spec_value, (TupleType, ListType)):
+            for key, value in opts:
+                if spec_key == key:
+                    break
+            else:
+                opts.append((spec_key, None))
+
     # We need to encode every keyword argument to a simple string, not the
     # unicode one, because ** expansion does not support it.
     for index, (key, value) in enumerate(opts):
diff --git a/src/common/connection_handlers.py b/src/common/connection_handlers.py
index 2eeff5b2c..e6bb1deb7 100644
--- a/src/common/connection_handlers.py
+++ b/src/common/connection_handlers.py
@@ -351,7 +351,7 @@ class ConnectionBytestream:
 		file_props['hash'] = hash_id
 		return
 
-	def _connect_error(self, to, _id, sid, code = 404):
+	def _connect_error(self, to, _id, sid, code=404):
 		''' cb, when there is an error establishing BS connection, or
 		when connection is rejected'''
 		if not self.connection or self.connected < 2:
diff --git a/src/common/gajim.py b/src/common/gajim.py
index 9a2ff9528..3511fe2d9 100644
--- a/src/common/gajim.py
+++ b/src/common/gajim.py
@@ -212,10 +212,10 @@ def get_server_from_jid(jid):
 	pos = jid.find('@') + 1 # after @
 	return jid[pos:]
 
-def get_nick_from_fjid(jid):
-	# fake jid is the jid for a contact in a room
-	# gaim@conference.jabber.no/nick/nick-continued
-	return jid.split('/', 1)[1]
+def get_resource_from_jid(jid):
+    tokens = jid.split('/', 1)
+    if len(tokens) > 1:
+        return tokens[1]
 
 def get_name_and_server_from_jid(jid):
 	name = get_nick_from_jid(jid)
diff --git a/src/roster_window.py b/src/roster_window.py
index 63d334571..c9201e4e7 100644
--- a/src/roster_window.py
+++ b/src/roster_window.py
@@ -849,7 +849,7 @@ class RosterWindow:
 		self.remove_contact(jid, account, force=True, backend=True)
 		return True
 		
-	def rename_group(self, old_name, new_name):
+	def rename_group(self, old_name, new_name, account):
 		"""
 		rename a roster group
 		"""
@@ -2396,7 +2396,7 @@ class RosterWindow:
 			else: # user is running svn
 				helpers.exec_command('%s history_manager.py' % sys.executable)
 		else: # Unix user
-			helpers.exec_command('%s history_manager.py &' % sys.executable)
+			helpers.exec_command('%s history_manager.py' % sys.executable)
 
 	def on_info(self, widget, contact, account):
 		'''Call vcard_information_window class to display contact's information'''
@@ -2756,7 +2756,7 @@ class RosterWindow:
 					win.show_title()
 			elif row_type == 'group':
 				# in C_JID column, we hold the group name (which is not escaped)
-				self.rename_group(old_text, new_text)
+				self.rename_group(old_text, new_text, account)
 
 		def on_canceled():
 			if 'rename' in gajim.interface.instances:
diff --git a/src/session.py b/src/session.py
index 7d8f5576f..dec454c18 100644
--- a/src/session.py
+++ b/src/session.py
@@ -86,7 +86,7 @@ class ChatControlSession(stanza_session.EncryptedStanzaSession):
 		'''dispatch a received <message> stanza'''
 		msg_type = msg.getType()
 		subject = msg.getSubject()
-		resource = gajim.get_nick_from_fjid(full_jid_with_resource)
+		resource = gajim.get_resource_from_jid(full_jid_with_resource)
 		if self.resource != resource:
 			self.resource = resource
 			if self.control and self.control.resource: