can.Map constructor fails if passed another Map

[zkat]

If you try and pass an instance of can.Map into the can.Map constructor, there's an error.

See: http://jsfiddle.net/mhraL/3/

[justinbmeyer]

What do you expect to happen? Clone?

[zkat]

Yeah. I know I can .attr() it, but the error can be really confusing, and this seems to have been a relatively recent change -- I ran into it while upgrading an app running on 2.0

[jawshooah]

Might be better for it to just return the argument. Maybe add a .clone() method that's just a wrapper for new can.Map(map.attr())?

[justinbmeyer]

@jawshooah, it might be better to clone. I think not returning a new instance when new is called would be confusing. Plus, I'm not sure that this can easily be made to happen with can.Construct.