I've taken a deeper look now and I'm stepping back. Uneasy package (modules contain byte code), probably dead (last release 01/2017, last commit 07/2017), it's not trivial to recreate a working setup (setup.cfg template etc.) - much overhead, and the reproducibility problem from it appears to be gone if upstream just updates (1.8 in flask-limiter, see #852482).
DS -- 4096R/DF5182C8 (sten...@debian.org) http://www.danielstender.com/
