std.test: ambiguity std::pair vs. std::tuple

[dani@…]

Seen with multiple compilers which support C++11's newly introduced std::tuple. Rather than pulling just the required entities from namespace 'std', the full namespace is pulled in instead.

For example, vc11 fails like this:

std.cpp
std.cpp(154) : error C2872: 'tuple' : ambiguous symbol
        could be 'std.cpp(78) : std::pair<_Ty1,_Ty2> tuple'
        with
        [
            _Ty1=std::string,
            _Ty2=int
        ]
        or 'VC\INCLUDE\utility(73) : std::tuple'

[dani@…]

Proposed fix: pull request ​https://github.com/boostorg/assign/pull/2

[James E. King, III]

​https://github.com/boostorg/assign/pull/21

The source repo/branch in PR #2 is no longer available.