Fix method put failing on junctions

[vrurg]

Resolves #4742. Aside of plain throwing (1|2).put also fix recursive cases when a junction is an eigenstate of another junction.

[lizmat]

What's so special about put? What not also say and print ?

[vrurg]

Because say and note do gist and it doesn't autothread. print works because it falls back to $*OUT.printwhich just autothreads.

But put is about Str and it uses nqp::concat. So, nqp::concat fails when it gets a Junction instance from .Str.