BUG #4697: to_tsvector hangs on input

The following bug has been logged online:

Bug reference:      4697
Logged by:          Peter Guarino
Email address:      peterguarino@earthlink.net
PostgreSQL version: 8.3.3
Operating system:   Suse 10.x
Description:        to_tsvector hangs on input
Details:

Certain strings involving the @ character cause the to_tsvector function to
hang and the postgres server process handling the connection to spin the cpu
at 100%. Attempts to gracefully kill the server process are unsuccessful and
a 'kill -9' becomes necessary. Here is an example of a such a string:
4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4@D4
@D4@D4@D4@D4@D4@D4@D2?C