Issue 24298: Fix signature() to properly unwrap wrappers around bound methods

Lib/inspect.py

@@ -2130,6 +2130,15 @@ def _signature_from_callable(obj, *,
     # Was this function wrapped by a decorator?
     if follow_wrapper_chains:
         obj = unwrap(obj, stop=(lambda f: hasattr(f, "__signature__")))
+        if isinstance(obj, types.MethodType):
+            # If the unwrapped object is a *method*, we might want to
+            # skip its first parameter (self).
+            # See test_signature_wrapped_bound_method for details.
+            return _signature_from_callable(
+                obj,
+                follow_wrapper_chains=follow_wrapper_chains,
+                skip_bound_arg=skip_bound_arg,
+                sigcls=sigcls)
 
     try:
         sig = obj.__signature__