[Bug libstdc++/64814] std::copy_n advances InputIterator one *less* time than necessary.

[alex-j-a at hotmail dot co.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64814

--- Comment #6 from Anquietas <alex-j-a at hotmail dot co.uk> ---
(In reply to Anquietas from comment #5)
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2014/n4296.pdf
The working copy for C++14, page 902 has the same specification as the other
PDF.