Comment 1 for bug 511072

I ran into this today too. Note that unwinding the stack and re signaling gives desired behavior.

This hangs:
(progn (make-package :foobar) (make-package :foobar))

The following does the right behavior:
(progn (make-package :foobar) (handler-case (make-package :foobar) (error (condition) (error condition))))

You can replicate this bug in raw lisp by going to the command prompt, typing `sbcl --no-userinit' and typing this form.
(progn (make-package :foobar) (sb-thread:make-thread (lambda () (make-package :foobar))))

It will hang, you will forced to kill sbcl.

I talked to the original reporter in #lisp earlier, who clued me on to this, thanks very much for taking the time to discuss this with me as otherwise I'd still be hacking at slime, thinking the bug was there.