Wrong message after updating primary key.

[MiguelSR]

If a model has a string primary key, you can change it via update. Everything works OK, but it prints a contradictory warning message ("Registry <old_id> doesn't exist")

Example:

/usr/src/app # python -m my_module config js create --id "foobar"
You are about to create the following entry:

id               'miao'

Are you sure? [y/N]: y
The following entry was created:

id               'miao'

# Then the following

/usr/src/app # python -m my_module config js update 'foobar' --id "barfoo"
You are about to update the following record:

id               'foobar'

With the following information:

id  barfoo

Are you sure? [y/N]: y
Changed 1 records.
Registry foobar does not exists.