Thanks for the review.  One note:

| +    def manifest_setup_ldargs
| I’d make all new methods private ones (i.e. leading underscore).

They aren't strictly private and are designed to be overridden by subclasses (although in practice, subclassing the compiler is much harder than it should be, so pywin32 monkey-patches the instance.)  This is actually the entire point of my updated patch - to give setup.py authors some level of control over the manifest behaviour.

I do intend forward-porting to 3.3 and also to check it is is too late for 3.2 (a quick check before implied it might be OK, but I'm not sure)