I believe there is a bug, or at least a not very nice feature in initdb.
If initdb does not succeed, it attempts to "exit_nicely". By default
this involved deleting the $PGDATA directory!! So if you have put other
things in you $PGDATA directory or (as in my case) you attempt to create
a database in an existing directory that contains lots of stuff that you
really, really wanted to keep, and initdb fails, initdb very "nicely"
deletes them for you if it fails.
It seems like it would be a whole lot "nicer" if initdb only deleted the
files that it attempted to create OR if the default was not to delete
anything.
In any case, I have changed the default on my installation to NEVER
"clean up" for me.
Jeff Collins