shell-mode: How to avoid the autocompletion of <<EOF

[Zorglups]

I posted this in comp.emacs but got absolutely no reply. I don't know if 
this was the right group.
Do you have an idea:

When writing shell code (in major shell-mode), if I type:
   <<
emacs will automatically expand it to:
  <<EOF

EOF
and put the point between the 2 lines.

How can I disable this ? I've been searching around without success.

Thanks.

Pierre.