Summary says it all.  Cloning for RHEL7.

+++ This bug was initially created as a clone of Bug #1122118 +++

Resolution:
The workaround is to edit /etc/rc.d/init.d/postgresql, but it only lasts until
the next postgresql upgrade.

Fix, add '-s /bin/bash' to runuser command lines in the /etc/init.d/postgresql
script.

Additional info:

--- Additional comment from Pavel Raiskup on 2014-07-22 17:52:22 CEST ---

(In reply to Andrew Riell from comment #0)
> Description of problem:
> SCAP security guide recommends that all UIDs < 500 (except root) be disabled
> from login by setting their shell to /sbin/nologin.  If you disable the
> postgres user this way, then postgresql will not start via 'service
> postgresql start'

Thanks for reporting this.

> As SCAP gets more integrated into RHEL in 7, and more people start using
> openscap functionality, this will become even more important.  So, even if
> this doesn't get fixed in RHEL 6, it needs to be fixed in RHEL 7.

Well, in RHEL 7 there is a problem only with 'postgresql-setup' and database
initialization (which is usually one-shot command).  The command 'systemctl
start postgresql' (or service postgresql start) itself is not affected.

> Fix, add '-s /bin/bash' to runuser command lines in the
> /etc/init.d/postgresql script.

You seem to be correct here.