Add duplicate parameter detection to preparser.

test/preparser/testcfg.py

Index: test/preparser/testcfg.py
diff --git a/test/preparser/testcfg.py b/test/preparser/testcfg.py
index 39b62c396de4c304d5b4c33b60463a45f45d86ab..c534fa1cf507e382ba09ebeab792b4b315643006 100644
--- a/test/preparser/testcfg.py
+++ b/test/preparser/testcfg.py
@@ -98,7 +98,6 @@ class PreparserTestConfiguration(test.TestConfiguration):
   def ParsePythonTestTemplates(self, result, filename,
                                executable, current_path, mode):
     pathname = join(self.root, filename + ".pyt")
-    source = open(pathname).read();
     def Test(name, source, expectation):
       throws = None
       if (expectation is not None):
@@ -118,8 +117,7 @@ class PreparserTestConfiguration(test.TestConfiguration):
           testsource = testsource.replace("$"+key, replacement[key]);
         Test(testname, testsource, expectation)
       return MkTest
-    eval(compile(source, pathname, "exec"),
-         {"Test": Test, "Template": Template}, {})
+    execfile(pathname, {"Test": Test, "Template": Template})
 
   def ListTests(self, current_path, path, mode, variant_flags):
     executable = join('obj', 'preparser', mode, 'preparser')
@@ -143,9 +141,9 @@ class PreparserTestConfiguration(test.TestConfiguration):
     filenames.sort()
     for file in filenames:
       # Each file as a python source file to be executed in a specially
-      # perparsed environment (defining the Template and Test functions)
+      # created environment (defining the Template and Test functions)
       self.ParsePythonTestTemplates(result, file,
-                                    executable, current_path, mode)
+                                      executable, current_path, mode)
     return result
 
   def GetTestStatus(self, sections, defs):