Get doctest to pass.  The problem was int/int -> float now.  There
were some cases where an int was assumed.

Also had to change the string of the exception when dividing and int by zero.
Not sure what the best error message should be.  Currently
  5 / 0 yields the message: ZeroDivisionError: float division

That isn't entirely correct.  But I'm not sure what else to do.
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 9c39ee8..1f89ac2 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -605,7 +605,7 @@
     ...     ...     print x,
     ...     0 1 2 3 4 5 6 7 8 9
     ...     >>> x/2
-    ...     6
+    ...     6.0
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
     >>> [e.lineno for e in test.examples]
@@ -680,7 +680,7 @@
     ...     >>> print x
     ...     12
     ...     >>> x/2
-    ...     6
+    ...     6.0
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
 
@@ -701,7 +701,7 @@
     ...     >>> print x
     ...     14
     ...     >>> x/2
-    ...     6
+    ...     6.0
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
     >>> doctest.DocTestRunner(verbose=True).run(test)
@@ -725,7 +725,7 @@
     Trying:
         x/2
     Expecting:
-        6
+        6.0
     ok
     (1, 3)
 """
@@ -739,7 +739,7 @@
     ...     >>> print x
     ...     12
     ...     >>> x/2
-    ...     6
+    ...     6.0
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
 
@@ -756,7 +756,7 @@
     Trying:
         x/2
     Expecting:
-        6
+        6.0
     ok
     (0, 3)
 
@@ -786,7 +786,7 @@
     Trying:
         x/2
     Expecting:
-        6
+        6.0
     ok
     (0, 3)
 
@@ -808,7 +808,7 @@
     ...     >>> x = 12
     ...     >>> print x/0
     ...     Traceback (most recent call last):
-    ...     ZeroDivisionError: integer division or modulo by zero
+    ...     ZeroDivisionError: float division
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
     >>> doctest.DocTestRunner(verbose=False).run(test)
@@ -825,7 +825,7 @@
     ...     >>> print 'pre-exception output', x/0
     ...     pre-exception output
     ...     Traceback (most recent call last):
-    ...     ZeroDivisionError: integer division or modulo by zero
+    ...     ZeroDivisionError: float division
     ...     '''
     >>> test = doctest.DocTestFinder().find(f)[0]
     >>> doctest.DocTestRunner(verbose=False).run(test)
@@ -836,7 +836,7 @@
         print 'pre-exception output', x/0
     Exception raised:
         ...
-        ZeroDivisionError: integer division or modulo by zero
+        ZeroDivisionError: float division
     (1, 2)
 
 Exception messages may contain newlines:
@@ -933,7 +933,7 @@
     Exception raised:
         Traceback (most recent call last):
         ...
-        ZeroDivisionError: integer division or modulo by zero
+        ZeroDivisionError: float division
     (1, 1)
 """
     def optionflags(): r"""