BUG #14968: package postgresql93-server-9.3.20-3PGDG.rhel7.x86_64 fails to start

The following bug has been logged on the website:

Bug reference: 14968
Logged by: Håkan Hagenrud
Email address: hakan(at)hagenrud(dot)nu
PostgreSQL version: 9.3.20
Operating system: Centos 7.4
Description:

Problem is in the systemd definition that is bundled in the package. The
variable:
TimeoutSec=infinity
is not supported on CentOS 7.4 as it uses systemd-219-42.el7_4.4.x86_64. And
the inifinity variable is supported from 229 of systemd. Hence

# It's not recommended to modify this file in-place, because it will be
# overwritten during package upgrades. If you want to customize, the
# best way is to create a file
"/etc/systemd/system/postgresql-9.3.service",
# containing
# .include /lib/systemd/system/postgresql-9.3.service
# ...make your changes here...
# For more info about custom unit files, see
#
http://fedoraproject.org/wiki/Systemd#How_do_I_customize_a_unit_file.2F_add_a_custom_unit_file.3F

# Note: changing PGDATA will typically require adjusting SELinux
# configuration as well.

# Note: do not use a PGDATA pathname containing spaces, or you will
# break postgresql-setup.
[Unit]
Description=PostgreSQL 9.3 database server
After=syslog.target
After=network.target

[Service]
Type=forking

User=postgres
Group=postgres

# Note: avoid inserting whitespace in these Environment= lines, or you may
# break postgresql-setup.

# Location of database directory
Environment=PGDATA=/var/lib/pgsql/9.3/data/

# Where to send early-startup messages from the server (before the logging
# options of postgresql.conf take effect)
# This is normally controlled by the global default set by systemd
# StandardOutput=syslog

# Disable OOM kill on the postmaster
OOMScoreAdjust=-1000

ExecStartPre=/usr/pgsql-9.3/bin/postgresql93-check-db-dir ${PGDATA}
ExecStart=/usr/pgsql-9.3/bin/pg_ctl start -D ${PGDATA} -s -w -t 300
ExecStop=/usr/pgsql-9.3/bin/pg_ctl stop -D ${PGDATA} -s -m fast
ExecReload=/usr/pgsql-9.3/bin/pg_ctl reload -D ${PGDATA} -s

# Do not set any timeout value, so that systemd will not kill postmaster
# during crash recovery.
TimeoutSec=infinity

[Install]
WantedBy=multi-user.target