BUG #12784: pg_relation_size has problems with case in index name

The following bug has been logged on the website:

Bug reference:      12784
Logged by:          Stefan Radomski
Email address:      gibheer@zero-knowledge.org
PostgreSQL version: 9.4.1
Operating system:   FreeBSD 10.1p5
Description:

I found a problem with indexes which have an uppercase letter in the name.
You can reproduce it with the following statements:

  create table unfindable("Test" text);
  create index on unfindable("Test");
  \d unfindable
  select pg_relation_size('unfindable_Test_idx');

It does work for tables with upper case characters in the name though.