error: cannot run hooks/pre-receive: No such file or directory

Hi all,

  I am trying to use a ruby script to reject commit with non-linear
history (*). However it keeps failing with the following message:

$ git push
Counting objects: 5, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 304 bytes, done.
Total 3 (delta 2), reused 0 (delta 0)
error: cannot run hooks/pre-receive: No such file or directory
To ssh://malat@gdcm.git.sourceforge.net/gitroot/gdcm/gdcm.old
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to
'ssh://malat@gdcm.git.sourceforge.net/gitroot/gdcm/gdcm.old'

I tried with something as simple as :

% cat pre-receive
#!/usr/bin/ruby
% which ruby
/usr/bin/ruby

Do I need to do something special with ruby ?

Thanks,
-- 
Mathieu