Constructor should make a copy

[nalimilan]

The following constructor should make a copy:

WeakRefStrings.jl/src/WeakRefStrings.jl

Line 289 in 7da08fd

(T::Type{<:StringArray})(arr::AbstractArray{<:STR}) = convert(T, arr)

This is not a problem in practice when the input is not a StringArray since a new array will have to be allocated, but we should add a method calling copy for StringArray inputs.