PEP 384 is listed as finished while 3121 is accepted so what if anything needs to be done here? I've checked https://docs.python.org/devguide/experts.html and nobody is listed against the signal module. The patch is C code which I don't have the knowledge to comment on, sorry about that.
The _signal extension module has been ported to the new multi-phase initialization API (PEP 489). See bpo-41111 "Convert a few stdlib extensions to the limited C API".