Understood, thanks!

A trivial fix for the integer comparison bug would solve my issue:

--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -527,21 +527,20 @@ signal_signal_impl(PyObject *module, int signalnum, PyObject *handler)
                          "signal number out of range");
         return NULL;
     }
-    if (handler == modstate->ignore_handler) {
+    if (PyCallable_Check(handler)) {
+        func = signal_handler;
+    }
+    else if (PyObject_RichCompareBool(handler, modstate->ignore_handler, Py_EQ) == 1) {
         func = SIG_IGN;
     }
-    else if (handler == modstate->default_handler) {
+    else if (PyObject_RichCompareBool(handler, modstate->default_handler, Py_EQ) == 1) {
         func = SIG_DFL;
-    }
-    else if (!PyCallable_Check(handler)) {
+    } else {
         _PyErr_SetString(tstate, PyExc_TypeError,
                          "signal handler must be signal.SIG_IGN, "
                          "signal.SIG_DFL, or a callable object");
         return NULL;
     }
-    else {
-        func = signal_handler;
-    }
 
     /* Check for pending signals before changing signal handler */
     if (_PyErr_CheckSignalsTstate(tstate)) {