recatalog existing databases after re-build from source

Going through the PLPython threads on the Planet, I realized that I needed plpython.  So I rebuilt PG with python,
expectingthat I could then re-catalog the databases.  But, not.  initdb, wants the data directory, which is where the
databasefiles are, and doesn't run if it's not empty.  The data directories have descriptive names like 16431, etc. 

These are only small test db's; losing them is not a big deal, but is there a way to get them back?

When I went to   createlang  I got the no "root" user message, which is why I went to look at initdb.  adduser says
thatpostgres user exists, which makes sense. 

thanks,
Robert