Segfault in Guile-1.4 and CVS Guile

[satchell]

The join-thread primitive seems to broken, when joining with a terminated
thread. 

For example
(define (thred-n n)
        (begin-thread 
         (sleep n)(display n)(newline)))
(join-thread   (thred-n 1))
(join-thread   (thred-n 0))

causes a segfault for me. This used to work, up to guile 1.3.4. A quick check
with gdb shows that coop_join in coop.c is being passed a NULL pointer. 

The correct fix is presumably to ensure that the thread pointer remains valid.
For now I have releived my symptoms by checking the pointer and returning if
NULL.

Julian Satchell
<address@hidden>