Periodic function in nlp-expr/001_010 implies infinitely many global minimizers

[cvanaret]

The instance nlp-expr/001_010 contains the periodic cos(y), y free, in its objective.
This means that any point (-1, pi + 2k pi, 1) is a global solution.

MINLPTests.jl/src/nlp-expr/001_010.jl

Line 32 in 46ce897

return check_solution([x, y, z], [-1, pi, 1], tol = primal_tol)

An SQP method may converge towards y = pi from the starting point, but a trust-region SLP method (that captures no curvature) may travel a bit and get y = 3pi.

[ccoffrin]

I am open to changing the test to resolve this issue. Let's hear what @odow thinks as well.

[odow]

This example proved challenging for Gurobi as well. Maybe we should just bound y.