Clear internal call error in 'L' format. Fixes #723201.

Backported to 2.4.

Lib/test/test_capi.py

 # Run the _testcapi module tests (tests for the Python/C API):  by defn,
 # these are all functions _testcapi exports whose name begins with 'test_'.
 
-import sys
+import sys, unittest
 from test import test_support
 import _testcapi
 
@@ -35,6 +35,12 @@ def TestThreadState():
         raise test_support.TestFailed, \
               "Couldn't find main thread correctly in the list"
 
+# Tests which use _testcapi helpers
+class OtherTests(unittest.TestCase):
+    def test_exc_L(self):
+        # This used to raise a SystemError(bad internal call)
+        self.assertRaises(TypeError, _testcapi.getargs_L, "String")
+
 try:
     _testcapi._test_thread_state
     have_thread_state = True
@@ -46,3 +52,9 @@ if have_thread_state:
     import threading
     t=threading.Thread(target=TestThreadState)
     t.start()
+
+def test_main():
+    test_support.run_unittest(OtherTests)
+
+if __name__=='__main__':
+    test_main()

Misc/NEWS

@@ -10,6 +10,8 @@ What's New in Python 2.5 alpha 1?
 Core and builtins
 -----------------
 
+- Bug #723201: Raise a TypeError for passing bad objects to 'L' format.
+
 - Bug #1124295: the __name__ attribute of file objects was
   inadvertently made inaccessible in restricted mode.
 

Python/getargs.c

@@ -610,6 +610,7 @@ convertsimple(PyObject *arg, char **p_format, va_list *p_va, char *msgbuf,
 		PY_LONG_LONG *p = va_arg( *p_va, PY_LONG_LONG * );
 		PY_LONG_LONG ival = PyLong_AsLongLong( arg );
 		if( ival == (PY_LONG_LONG)-1 && PyErr_Occurred() ) {
+			PyErr_Clear();
 			return converterr("long<L>", arg, msgbuf, bufsize);
 		} else {
 			*p = ival;