gypv8sh; only catch CalledProcessException, rather than Exception

tools/gypv8sh.py

 #!/usr/bin/env python
 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """This script is used by chrome_tests.gypi's js2webui action to maintain the
 argument lists and to generate inlinable tests.
 
 Usage:
   python tools/gypv8sh.py v8_shell mock.js test_api.js js2webui.js \
@@ skipping 26 matching lines @@
       inputfile, inputrelfile, cxxoutfile, jsoutfile) = args
   arguments = [js2webui, inputfile, inputrelfile, cxxoutfile, test_type]
   cmd = [v8_shell, '-e', "arguments=" + json.dumps(arguments), mock_js,
          test_api, js2webui]
   if opts.verbose or opts.impotent:
     print cmd
   if not opts.impotent:
     try:
       subprocess.check_call(cmd, stdout=open(cxxoutfile, 'w'))
       shutil.copyfile(inputfile, jsoutfile)
-    except Exception, ex:
+    except subprocess.CalledProcessException, ex:
+      print "returncode", ex.returncode
       print ex
       os.remove(cxxoutfile)
       os.remove(jsoutfile)
       sys.exit(1)
 
 if __name__ == '__main__':
  sys.exit(main())