[Chicken-users] strange bug - help needed

[F. Wittenberger]

Until I updated to svn trunk today, my program did work fine (as far as
I ported it already).

Now I see 

Error: call of non-procedure: #<unbound value>


The stracktrace is weird:

        Call history:

        util-chicken.scm: 543  create-pipe              
        util-chicken.scm: 544  process-fork             
        util-chicken.scm: 547  sudo!            
        util-chicken.scm: 549  duplicate-fileno         
        util-chicken.scm: 550  duplicate-fileno         
        util-chicken.scm: 551  close-all-ports-except           
        util-chicken.scm: 552  thunk            
        util-chicken.scm: 561  process-execute                  <--

...that is if I don't print the value of "process-execute" - if I do,
it runs different:

#<procedure (process-execute filename1095 . g10941096)>
Error: call of non-procedure: #<unbound value>

        Call history:

        srfi19.scm: 325  tm:date-printer                
        util-chicken.scm: 1311 current-error-port               
        util-chicken.scm: 1311 display          
        util-chicken.scm: 1311 current-error-port               
        util-chicken.scm: 1311 display          
        util-chicken.scm: 1311 current-error-port               
        util-chicken.scm: 1311 current-error-port               
        util-chicken.scm: 1311 flush-output                     <--

and this print statement is really the only difference.

So How do I debug that one?