Trac #34535: Segfault when floor dividing in infinite polynomial ring

{{{
sage: R.<z> = InfinitePolynomialRing(QQ)
sage: (z[4] + z[5])//(z[4] + z[5])
------------------------------------------------------------------------
(no backtrace available)
------------------------------------------------------------------------
Unhandled SIGSEGV: A segmentation fault occurred.
This probably occurred because a *compiled* module has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Python will now terminate.
------------------------------------------------------------------------
/Users/trevorkarn/Applications/sage/src/bin/sage-python: line 2: 49123
Segmentation fault: 11  sage -python "$@"
}}}

URL: https://trac.sagemath.org/34535
Reported by: tkarn
Ticket author(s): Trevor K. Karn
Reviewer(s): Travis Scrimshaw