[Pkg-matrix-maintainers] Bug#1129026: matrix-synapse: pympler was removed from debian, still recommended

[grin]

> (but the memory management consequences may be relevant).

It is only used in ./util/caches/lrucache.py to guess at cached object size, and return 0 if it's not available.
Actually only used when caches.TRACK_MEMORY_USAGE is True, which I guess normally isn't.

So my guess is that it won't be missed, but old version being available defintely breaks the package.