Error in copying JuMP.Model

Hello,
when I copy a model that uses the PiecewiseLinearOpt.jl this error occurs:
"
ERROR: LoadError: Error copying extension dictionary. Is `copy` defined for all your user types?
in copy(::JuMP.Model) at C:\Users\blabla\v0.5\JuMP\src\JuMP.jl:297
"

JuMP.jl:297 contains
copy(source.ext[key])

When I print more details in I obtain:
key = :PWL
source.ext = Dict{Symbol,Any}(Pair{Symbol,Any}(:PWL,PiecewiseLinearOpt.PWLData(768)))

So I presume that PiecewiseLinearOpt does not implement a copy method, am I correct?

Is there any way to have an implementation... very soon? :)

Thanks,
Andrea