Implement an idea by Paul Rubin:
Change pickling format for bools to use a backwards compatible
encoding. This means you can pickle True or False on Python 2.3
and Python 2.2 or before will read it back as 1 or 0. The code
used for pickling bools before would create pickles that could
not be read in previous Python versions.
diff --git a/Lib/test/test_bool.py b/Lib/test/test_bool.py
index ee5d5fa..0a60a3b 100644
--- a/Lib/test/test_bool.py
+++ b/Lib/test/test_bool.py
@@ -224,5 +224,11 @@
veris(cPickle.loads(pickle.dumps(True)), True)
veris(cPickle.loads(pickle.dumps(False)), False)
+# Test for specific backwards-compatible pickle values
+vereq(pickle.dumps(True), "I01\n.")
+vereq(pickle.dumps(False), "I00\n.")
+vereq(cPickle.dumps(True), "I01\n.")
+vereq(cPickle.dumps(False), "I00\n.")
+
if verbose:
print "All OK"