Armin Rigo's fix & test for

[ 729622 ] line tracing hook errors

with massaging from me to integrate test into test suite.

Lib/test/test_trace.py

@@ -221,6 +221,27 @@ class RaisingTraceFuncTestCase(unittest.TestCase):
     def test_exception(self):
         self.run_test_for_event('exception')
 
+    def test_trash_stack(self):
+        def f():
+            for i in range(5):
+                print i  # line tracing will raise an exception at this line
+
+        def g(frame, why, extra):
+            if (why == 'line' and
+                frame.f_lineno == f.func_code.co_firstlineno + 2):
+                raise RuntimeError, "i am crashing"
+            return g
+
+        sys.settrace(g)
+        try:
+            f()
+        except RuntimeError:
+            # the test is really that this doesn't segfault:
+            import gc
+            gc.collect()
+        else:
+            self.fail("exception not propagated")
+
 
 # 'Jump' tests: assigning to frame.f_lineno within a trace function
 # moves the execution position - it's how debuggers implement a Jump