On Windows, we suddenly find, strftime() may return "" for an

unsupported format string.  (I guess this is because the logic for
deciding whether to reallocate the buffer or not has been improved.)
This caused the test code to crash on result[0].  Fix this by assuming
an empty result also means the format is not supported.

Lib/test/test_strftime.py

@@ -99,7 +99,7 @@ def strftest(now):
             print "Standard '%s' format gave error:" % e[0], error
             continue
         if re.match(e[1], result): continue
-        if result[0] == '%':
+        if not result or result[0] == '%':
             print "Does not support standard '%s' format (%s)" % (e[0], e[2])
         else:
             print "Conflict for %s (%s):" % (e[0], e[2])