plugin_e2ee: correctly pass realjid to decrypt call in MUC

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

poezio/plugin_e2ee.py

@@ -378,17 +378,18 @@ class E2EEPlugin(BasePlugin):
         # fine with this so let them handle it.
         jid = message['from']
 
-        muctab = None
+        muctab: Optional[MucTab] = None
         if isinstance(tab, PrivateTab):
             muctab = tab.parent_muc
             jid = None
 
-        if isinstance(muctab, MucTab):
+        if muctab is not None or isinstance(tab, MucTab):
+            if muctab is None:
+                muctab = tab  # type: ignore
             nick = message['from'].resource
-            for user in muctab.users:
-                if user.nick == nick:
-                    jid = user.jid or None
-                    break
+            user = muctab.get_user_by_name(nick)  # type: ignore
+            if user is not None:
+                jid = user.jid or None
 
         self.decrypt(message, jid, tab)