BUG #14014: postgresql95-setup script determines PGDATA wrongly

The following bug has been logged on the website:

Bug reference: 14014
Logged by: leonty
Email address: tigreavecdesailes(at)gmail(dot)com
PostgreSQL version: 9.5.1
Operating system: RHEL 7.2
Description:

The script postgresql95-setup tries to determine the PGDATA directory two
times:

1. first time using a systemctl call. That's ok, systemctl knows all
possible unit file places and processes correctly the drop-ins (a directory
in /etc/systemd/system/ ending with '.d' where partial configurations are
stored).

2. second time (why at all??) in a few lines using sed utility to parse the
unit file. That's wrong because drop-in directories won't be considered and
overridden PGDATA environment is missed.

How to reproduce:
create /etc/systemd/system/postgresql-9.5.service.d/pgdata.conf with the
following content:
[Service]
Environment=PGDATA=/tmp/another_postgresql_location

run 'postgresql95-setup initdb', get a successful result message, then run
'systemctl start postgresql-9.5'. The database won't start, the log contains
a message that the database is not initialized.

How to fix:
Probably it's just enough to delete the second try of parsing the unit file
from postgresql95-setup script. Lines 103-104:
# Get data directory from the service file
PGDATA=`sed -n 's/Environment=PGDATA=//p' "${SERVICE_FILE}"`