What does this error message means ?

I did a query:
discovery=>  select a.msg_id,b.key_id into qq   from publications  a, keywords b where a.title ~* b.name and b.key_id in ( select key_id from keywords);
ERROR:  regcomp failed with error empty (sub)expression

I found what's the problem:

in a.title ~* b.name b.name = '' (NOT NULL)

discovery=> select * from keywords where key_id=449;
key_id|name
------+----
   449|    
(1 row)


I consider this as a bug in regcomp code. rexx, perl match empty string ! 

This happens with slightly outdated (week ago) 6.5 cvs

	Regards,

		Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83


Sat, 12 Jun 1999 05:51:58 +0400 (MSD)
Oleg Bartunov <oleg@sai.msu.su>
BUG: ERROR:  regcomp failed with error empty (sub)expression