autoload-credentials does not quit on cloud name

[Anastasia]

'autoload-credentials' offers to quit when user is prompted for a cloud name. However, if user tries to quit, the command ignores it and keeps going:

$ juju autoload-credentials

Looking for cloud and credential information locally...

1. LXD credential "localhost" (new)
Select a credential to save by number, or type Q to quit: 1

Select the cloud it belongs to, or type Q to quit []: q

No cloud name entered.

1. LXD credential "localhost" (new)
Select a credential to save by number, or type Q to quit:

[Anastasia (anastasia-macmood)]

PR against develop: https://github.com/juju/juju/pull/10450