Bug#1108920: libbctoolbox-dev: cannot bind non-const lvalue reference of type "pumpstream&" to an rvalue of type "pumpstream"

[Frank Heckenbach]

Tried again, still present in the stable version.

Occurs with "-std=c++23".

Current upstream version seems to have two such affected functions,
but patch is analogous.

Tried to report it upstream, but upstream requires a login, and
registration on that page is broken.