pg_ctl non-idempotent behavior change

After 87306184580c9c49717, if the postmaster dies without cleaning up (i.e.
power outage), running "pg_ctl start" just gives this message and then
exits:

pg_ctl: another server might be running

Under the old behavior, it would try to start the server anyway, and
succeed, then go through recovery and give you back a functional system.

From reading the archive, I can't really tell if this change in behavior
was intentional.

Anyway it seems like a bad thing to me. Now the user has a system that
will not start up, and is given no clue that they need to remove
"postmaster.pid" and try again.

The behavior here under the new "-I" flag seems no better in this
situation. It claims the server is running, when it only "might" be
running (and in fact is not running).

Cheers,

Jeff