I'd like to make the case for a fix in the code again. Our use case is, I believe, the same as Vilya's. We want to temporarily set a signal handler from Python and then restore the previous handler. This is fairly straightforward for Python handler functions, and SIG_DFL and SIG_IGN, but it breaks if anything has set a C level signal handler.

The opaque wrapper object is a solution that had occurred to me too. Another option would be a context manager implemented in C (I assume context managers can be written in C) which can set one or more signal handlers on entry, and restore them on exit.