BUG #5021: ts_parse doesn't recognize email addresses with underscores

The following bug has been logged online:

Bug reference:      5021
Logged by:          Dan O'Hara
Email address:      danarasoftware@gmail.com
PostgreSQL version: 8.3.7
Operating system:   win32
Description:        ts_parse doesn't recognize email addresses with
underscores
Details:

In the following example,

select distinct token as email
from ts_parse('default', ' first_last@yahoo.com '   )
where tokid = 4

ts_parse returns last@yahoo.com rather than first_last@yahoo.com  It seems
that any text prior to the underscore is truncated.  If the portion
following the underscore is only numeric, such as this example,

select distinct token as email
from ts_parse('default', ' bill_2000@yahoo.com '   )
where tokid = 4

then ts_parse returns nothing at all.

section 3.2.3 of RFC 5322 indicates that underscores are valid characters in
an email address.

http://tools.ietf.org/html/rfc5322