import xmpp only when needed in helpers.py so decode_string is loaded before. see #4764

src/common/helpers.py

@@ -44,7 +44,6 @@
 
 from i18n import Q_
 from i18n import ngettext
-import xmpp
 
 try:
 	import winsound # windows-only built-in module for playing wav
@@ -1347,6 +1346,7 @@ def prepare_and_validate_gpg_keyID(account, jid, keyID):
 	return keyID
 
 def update_optional_features(account = None):
+	import xmpp
 	if account:
 		accounts = [account]
 	else: