Followup to issue #11140 and r88682: also patch _dummy_thread.
Patch by Aymeric Augustin.
diff --git a/Lib/_dummy_thread.py b/Lib/_dummy_thread.py
index ed50520..13b1f26 100644
--- a/Lib/_dummy_thread.py
+++ b/Lib/_dummy_thread.py
@@ -24,11 +24,7 @@
 # imports are done when needed on a function-by-function basis.  Since threads
 # are disabled, the import lock should not be an issue anyway (??).
 
-class error(Exception):
-    """Dummy implementation of _thread.error."""
-
-    def __init__(self, *args):
-        self.args = args
+error = RuntimeError
 
 def start_new_thread(function, args, kwargs={}):
     """Dummy implementation of _thread.start_new_thread().