gistfile1.txt

Problem:

pg_hba.conf:
local   all         all                               md5
host    all         all         127.0.0.1/32          md5
host    all         all         ::1/128               md5

pg_ident.conf:
(blank, just comments)

bash-3.2# psql -U postgres
Password for user postgres: (Correct Password)
psql: FATAL:  password authentication failed for user "postgres"

Solution:
change pg_hba.conf to:
local   all         all                               trust
host    all         all         127.0.0.1/32          trust
host    all         all         ::1/128               trust

Then change password, and change back to md5(or other)