Like vs '=' bug with indexing

I am reposting this because I'm not sure it actually
made it to the list.

I have a function to transform text into a
pseudo-metaphone variable, take this example:

cddbsql=# select song, metatext(song) from cdsongs
where metatext(song) like metatext('born to run')
limit 3 ;
song | metatext
-------------+----------
Born To Run | brntorn
Born To Run | brntorn
Born To Run | brntorn
(3 rows)

Here is the problem: Depending on whether there is an
index or not, 'like' behaves differently. Here is a
transcript:

cddbsql=# select song, metatext(song) from cdsongs
where metatext(song) like metatext('born to run')
limit 1 ;
song | metatext
-------------+----------
Born To Run | brntorn
(1 row)

cddbsql=# create index cdsongs_meta_song on cdsongs
(metatext(song)) ;
CREATE
cddbsql=# select song, metatext(song) from cdsongs
where metatext(song) like metatext('born to run')
limit 1 ;
song | metatext
------+----------
(0
rows)

This happens in both 7.0 and
7.1.

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