[Bug libstdc++/115399] std::tr2::dynamic_bitset shift behaves differently from std::bitset

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115399

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
And 13.4 and 12.5