BUG #14957: service initdb fails (initdbcmd run in background)

The following bug has been logged on the website:

Bug reference:      14957
Logged by:          Ben Thorner
Email address:      benthorner@hotmail.co.uk
PostgreSQL version: 9.6.6
Operating system:   RHEL 6.8
Description:

Running 'service postgresql-9.6 initdb' fails in 9.6.6-3 due to $initdbcmd
being run in the background. This is causing the subsequent init script
checks to fail and also does not allow for $initdbcmd to complete. Looking
at an exsting installation at version 9.6.6-1 I can see $initdbcmd is run in
the foreground, indicating this is a regression.