plugin XEP-0329: fix root node retrieval and _fileSendingRequestTrigger return value

sat/plugins/plugin_xep_0329.py

@@ -212,9 +212,6 @@ class ShareNode(object):
                 '[{profile}]').format(path=path, profile=client.profile))
             raise exceptions.PermissionError("illegal path elements")
 
-        if not path_elts:
-            raise exceptions.DataError(_("path is invalid: {path}").format(path=path))
-
         node = client._XEP_0329_root_node
 
         while path_elts:
@@ -448,7 +445,7 @@ class XEP_0329(object):
             size=size,
             data_cb=lambda data: hasher.update(data),
         )
-        return False, True
+        return False, defer.succeed(True)
 
     # common methods