BUG #11769: function host(character) does not exist

The following bug has been logged on the website:

Bug reference: 11769
Logged by: Sep Dehpour
Email address: sep(at)zepworks(dot)com
PostgreSQL version: 9.3.5
Operating system: Ubuntu 14.04.1 LTS
Description:

Hello,

I'm running on 2 different nodes:
PostgreSQL 9.3.5 on x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu
4.8.2-19ubuntu1) 4.8.2, 64-bit

Everything is the same on both. Right now if I run this on both nodes:
SELECT * FROM "axes_accessattempt" WHERE
HOST("axes_accessattempt"."ip_address") = '192.168.121.1';

One works, and on the other I get:
RROR: function host(character) does not exist
LINE 1: SELECT * FROM "axes_accessattempt" WHERE HOST("axes_accessat...
^
HINT: No function matches the given name and argument types. You might need
to add explicit type casts.

The only way that things get back to work is to delete the tables and
recreate them. It is very annoying.
This issue happens from time to time. I have not found a pattern yet.