To reproduce:

.gurgitate-rules:

filter('spamc') do
  save("=Test")
  return
end

Throws this:
Sat Mar 24 21:37:13 +0100 2007 Filtering with spamc
Sat Mar 24 21:37:13 +0100 2007 Error while executing /home/mrb/.gurgitate-rules: exit
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:235:in
`exit'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:235:in
`filter'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:222:in
`popen'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:222:in
`filter'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /home/mrb/.gurgitate-rules:1:in `process'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:247:in
`eval'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:249:in
`process'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:247:in
`each'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/lib/gurgitate-mail.rb:247:in
`process'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/gems/gurgitate-mail-1.8.1/bin/gurgitate-mail:50
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/bin/gurgitate-mail:18:in `load'
Sat Mar 24 21:37:13 +0100 2007 Backtrace: /var/lib/gems/1.8/bin/gurgitate-mail:18


When i cat a mail into gurgitate-mail.

Date: 2007-04-21 05:49
Sender: Dave Brown

Problem solved (with a one-_byte_ change).  The fix will be in
gurgitate-mail 1.8.4, due out later today.

Date: 2007-04-21 02:09
Sender: Dave Brown

Reproduced successfully.  Thank you for the report, I will investigate
and fix this problem.