BUG #14054: "create index using gist ..." on large table never completes.

The following bug has been logged on the website:

Bug reference:      14054
Logged by:          Tim Singletary
Email address:      tsingle@muddypaddock.com
PostgreSQL version: 9.5.1
Operating system:   osx 10.11.4
Description:

"create index using gist ..." ran for over three days on 100 million row
table; completes within a couple hours on a 10 million row table.

Had previously tried same experiment with 9.2.3 on a Linux box where the 100
million row table's index built within 5 hours.

The table looks like

        CREATE TABLE mock (
            handle INT NOT NULL
            ,lowest INT NOT NULL
            ,highest INT NOT NULL
            ,stuff TEXT
        );

Data was randomly generated.

The command that never completes is:

create index on mock using gist (handle,(int4range(lowest,highest,'[]')));