ST_UNION(linestring, linestring) returns a multilinestring

Hi all,

This is very annoying. I have two linestrings the join end-to-end and I 
want to build a new single linestring by merging the two. How can I do this?

Thanks,
   -Steve

select astext( 
ST_Union( 
         ST_GeomFromText('LINESTRING(35.5269251710001 
33.891749555,35.527091166 33.8917984710001)'),
ST_GeomFromText('LINESTRING(35.527091166 
33.8917984710001,35.5274352000001 33.8918998510001,35.528236559 
33.8919810230001)')                                    ));

               astext 

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  MULTILINESTRING((35.5269251710001 33.891749555,35.527091166 
33.8917984710001),(35.527091166 33.8917984710001,35.5274352000001 
33.8918998510001,35.528236559 33.8919810230001))
(1 row)