bool / vacuum full bug followup

OK, this is just beyond weird.  I swear to GOD that my table size was
growing.  I'm on a workstation that doesn't accept connections from
anybody but me.

I was running 7.2 for weeks.
I created a simple table:
    create table test (buf text, yn bool);
I run an explain:
    explain select * from test where yn=true;
I run an analyze:
    analyze;
I update the table:
    update test set yn=true where yn=true;
    update test set yn=true where yn=true;
    update test set yn=true where yn=true;
I do a REGULAR vacuum:
    vacuum;

And after that, the table started growing after all vacuum fulls.  I can't
reproduce it now.  I blew away the table, recreated it, and now it doesn't
do that.  I blew away the database, and installed 7.2.1 and it won't do
it.  I reinstalled 7.2 and blew away the database and it still won't do
it.

So, I don't know why it WAS doing it, but it isn't now.  And of course,
it's my personal workstation, so no log files.  :-(  I'll see if I can
reproduce this though, as I've seen similar problems pop up once in the
past with a seldom vacuumed database that reached a point where it stopped
freeing dead tuples.  Very bothersome.