Update reference body again

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

poezio_omemo/__init__.py

@@ -141,7 +141,7 @@ class Plugin(E2EEPlugin):
             )
             # Heartbeats will return a None body.
             if body is not None:
-                body = body.decode('utf-8')
+                message['body'] = body.decode('utf-8')
         except (MissingOwnKey,):
             # The message is missing our own key, it was not encrypted for
             # us, and we can't decrypt it.
@@ -173,8 +173,7 @@ class Plugin(E2EEPlugin):
             self.display_error('An error occured while attempting decryption.\n%r' % exn)
             raise
 
-        if body is not None:
-            message['body'] = body
+        return None
 
     async def encrypt(self, message: Message, jids: Optional[List[JID]], _tab) -> None:
         if jids is None: