As it turned out, we had two bugs luring in the code base,
with the happy result of one cancelling out the adverse effects of the other
:-D
- a mistake in the invocation of the Itertools (transform, filter,...)
caused them to move and consume any input passed by forwarding, instead
of consuming only the RValue references.
- but util::join did an extraneous copy on its data source, meaning that
in all relevant cases where a *copy* got passed into the Itertools,
only that spurious temporary was consumed by Bug #1.
(Note that most usages of Itertools rely on RValues anyway, since the whole
point of Itertools is to write concise in-line transformation pipelines...)
*** Added additional testcode to prove util::stringify() behaves correct
now in all cases.