I guess exception handling is supposed to check __subclasscheck__

test/tests/exception_subclasscheck.py

+# expected: fail
+# - don't support this stuff yet
+
+# Exception-catching is supposed to go through __subclasscheck__
+
+class M(type):
+    def __instancecheck__(self, instance):
+        print "instancecheck", instance
+        return True
+
+    def __subclasscheck__(self, sub):
+        print "subclasscheck", sub
+        return True
+
+class E(Exception):
+    __metaclass__ = M
+
+print 1
+print isinstance(E(), E) # does not print anything due to special-casing
+print 2
+print isinstance(1, E)
+print 3
+
+# This calls __subclasscheck__ twice...?
+try:
+    raise E()
+except E:
+    pass
+
+print 4
+
+try:
+    raise Exception()
+except E:
+    pass
+
+print 5