pg_ctl restart issue with relative paths

Hi,

I have noticed that, using pg_ctl, if you start Postgres using a
relative path, then attempt to restart it from anywhere else, it
fails.

Example:

thom(at)swift /tmp $ pg_ctl -D primary start
server starting
thom(at)swift /tmp $ pg_ctl -D primary restart
waiting for server to shut down.... done
server stopped
server starting
thom(at)swift /tmp $ cd
thom(at)swift ~ $ pg_ctl -D /tmp/primary restart
waiting for server to shut down.... done
server stopped
server starting
thom(at)swift ~ $ postgres cannot access the server configuration file
"/home/thom/primary/postgresql.conf": No such file or directory

thom(at)swift ~ $ cd /tmp/primary
thom(at)swift /tmp/primary $ pg_ctl -D /tmp/primary restart
pg_ctl: PID file "/tmp/primary/postmaster.pid" does not exist
Is server running?
starting server anyway
server starting
thom(at)swift /tmp/primary $ postgres cannot access the server
configuration file "/tmp/primary/primary/postgresql.conf": No such
file or directory

thom(at)swift /tmp/primary $ cd ..
thom(at)swift /tmp $ pg_ctl -D /tmp/primary restart
pg_ctl: PID file "/tmp/primary/postmaster.pid" does not exist
Is server running?
starting server anyway
server starting

This issue does not occur if stopping then starting. I suspect the
blame lies with postmaster.opts not storing the resolved absolute
path.

OS: Linux Mint 13 64-bit
PostgreSQL version: 9.1.6 at least (just the stable version I tested
on), and git master

--
Thom