Charles Waldman writes:

gvanrossum · gvanrossum · commit 84219682fbfb · 2000-04-21T20:49:58.000Z
"""
In the course of debugging this I also saw that cPickle is
inconsistent with pickle - if you attempt a pickle.load or pickle.dump
on a closed file, you get a ValueError, whereas the corresponding
cPickle operations give an IOError.  Since cPickle is advertised as
being compatible with pickle, I changed these exceptions to match.
"""
diff --git a/Lib/test/test_cpickle.py b/Lib/test/test_cpickle.py
@@ -79,18 +79,18 @@ def dotest():
     f.close()
     try:
         cPickle.dump(123, f)
-    except IOError:
+    except ValueError:
         pass
     else:
-        print "dump to closed file should raise IOError"
+        print "dump to closed file should raise ValueError"
     f = open(fn, "r")
     f.close()
     try:
         cPickle.load(f)
-    except IOError:
+    except ValueError:
         pass
     else:
-        print "load from closed file should raise IOError"
+        print "load from closed file should raise ValueError"
     os.remove(fn)
 
     # Test specific bad cases
