Index: Modules/signalmodule.c
===================================================================
--- Modules/signalmodule.c	(revision 87729)
+++ Modules/signalmodule.c	(working copy)
@@ -981,9 +981,25 @@
     return 0;
 }
 
+static void
+_PyOS_ClearPendingSignals(void)
+{
+    int i;
+    if (!is_tripped)
+        return;
+    is_tripped = 0;
+    for (i = 1; i < NSIG; ++i) {
+        Handlers[i].tripped = 0;
+    }
+}
+
 void
 PyOS_AfterFork(void)
 {
+    /* Clear the signal flags after forking so that they aren't handled
+     * in both processes if they came in just before the fork() but before
+     * the interpreter had an opportunity to call the handlers.  issue9535. */
+    _PyOS_ClearPendingSignals();
 #ifdef WITH_THREAD
     PyEval_ReInitThreads();
     main_thread = PyThread_get_thread_ident();