dual status not supported by all solvers

[rb004f]

Line 23 of solution.jl assumes that JuMP.dual_status() is implemented for all solvers, however it can fail when that is not the case (for example, SCIP.jl currently doesn not implement the function). I stashed one way of doing this in the branch rbent-safety-checks, but I suspect there is a more elegant way of doing this

[ccoffrin]

I am checking into this. I thought it was required for all solvers to support this parameter. Stay tuned.

[rb004f]

Yeah, dual_status failed for me with SCIP 0.9.4, jump 0.20.1

[ccoffrin]

@rb004f, I think the conclusion here is that there was a bug in the SCIP API. Can we close those issue and delete the associated branch?