So far as I know, once the data gets through the HTTP/HTTPS layer, the FastCGI layer doesn’t care.   But what I have always done is to nevertheless clearly-separate the HTTPS from the HTTP traffic handlers, since one is thought of as secure and the other is not.   I want to keep them at arm’s length and maybe on a different set of servers, due to the classification of the data which each one handles.   Both sets of handlers actually use (or require) duplicate copies of the same code-base, however.