Comment 1 for bug 1119552

I created a fix and opened a pull request for this:

https://github.com/dlitz/pycrypto/pull/36

As I say in the comment, I branched it off from my pkcs8 branch mainly for cosmetic reason.
By changing one line it could be applied directly to main.

One last one. RFC 4055 only talks about SHA1/2 algorithms. RFC 3447 (PKCS#1 v2.1) says the same thing,
but it also says that any MD2/5-based signature must have the parameters (field with value NULL).
It is still mandatory in that case.