[Ray: Core] Ray can hang when getting an ObjectRef from an unknown environment

[pabloem]

What happened + What you expected to happen

In the following script, the last statement hangs:

ray.init()
myref = ray.put('mystringhere')
ray.shutdown()

ray.init()
ray.get(myref)   # This statement hangs

What I would expect is for it to eventually throw an exception.

Versions / Dependencies

I ran this on Ray 2.0 and a recent Linux Debian

Reproduction script

ray.init()
myref = ray.put('mystringhere')
ray.shutdown()

ray.init()
ray.get(myref)   # This statement hangs

Issue Severity

Medium: It is a significant difficulty but I can work around it.

[rkooo567]

This is not supported. But I think we should raise a better error message