BUG #5276: pg_ctl reads data directory on -D instead of postgresql.conf directoryh

The following bug has been logged online:

Bug reference:      5276
Logged by:          James Bellinger
Email address:      jfb@zer7.com
PostgreSQL version: 8.4.2
Operating system:   Ubuntu 9.10
Description:        pg_ctl reads data directory on -D instead of
postgresql.conf directoryh
Details:

While on startup, pg_ctl (correctly) looks in the directory specified by -D
for postgresql.conf, and then uses that to determine the data directory,
when stopping it actually expects the directories to be the same and in
doing so looks for the PID file in the given directory. As a result, on
start one needs to use the .conf directory with -D, and on stop the data
directory.

It's not a big deal, but for consistency's sake it ought to read the .conf
file to get the data directory on stop.