Clear pending signals from child process after fork()

In existing Python, pending signals are inherited by children of a
process, as demonstrated by pressing C-c in the middle of the
following program:

"""
import os, sys, time, threading
def do_fork():
    while True:
        if not os.fork():
            print 'hello from child'
            sys.exit(0)
        time.sleep(0.5)
t = threading.Thread(target=do_fork)
t.start()
t.join()
"""

diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index f8ed718..3b8ddf3 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -145,6 +145,7 @@ PyAPI_FUNC(void) PyByteArray_Fini(void);
 
 /* Stuff with no proper home (yet) */
 PyAPI_FUNC(char *) PyOS_Readline(FILE *, FILE *, char *);
+PyAPI_FUNC(void) PyOS_ClearPendingSignals(void);
 PyAPI_DATA(int) (*PyOS_InputHook)(void);
 PyAPI_DATA(char) *(*PyOS_ReadlineFunctionPointer)(FILE *, FILE *, char *);
 PyAPI_DATA(PyThreadState*) _PyOS_ReadlineTState;
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 8a23e65..6554326 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -3614,6 +3614,13 @@ posix_fork1(PyObject *self, PyObject *noargs)
     _PyImport_AcquireLock();
     pid = fork1();
     if (pid == 0) {
+        /*
+          If a signal is received by the child after the fork but
+          before clearing pending signals, it will be lost.  Since
+          there is no cross-platform way of disabling signals, however,
+          there's not much we can do except hope.
+        */
+        PyOS_ClearPendingSignals();
         /* child: this clobbers and resets the import lock. */
         PyOS_AfterFork();
     } else {
@@ -3647,6 +3654,7 @@ posix_fork(PyObject *self, PyObject *noargs)
     _PyImport_AcquireLock();
     pid = fork();
     if (pid == 0) {
+        PyOS_ClearPendingSignals();
         /* child: this clobbers and resets the import lock. */
         PyOS_AfterFork();
     } else {
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index 9dc781d..a822d47 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -927,6 +927,18 @@ PyOS_FiniInterrupts(void)
     finisignal();
 }
 
+void
+PyOS_ClearPendingSignals(void)
+{
+    int i;
+    if (!is_tripped)
+        return;
+    is_tripped = 0;
+    for (i = 1; i < NSIG; i++) {
+        Handlers[i].tripped = 0;
+    }
+}
+
 int
 PyOS_InterruptOccurred(void)
 {