wp-cli/wp-cli — pull request #435 by scribu (2013-08-21 20:07:29+00:00)
Title: `wp core config` fails on any empty parameter

Steps to reproduce:

```
rm wp-config.php
wp core config --dbname=''
```

Expected output:

```
Warning: missing --dbuser parameter
usage: wp core config --dbname= --dbuser= [--dbpass=] [--dbhost=] [--dbprefix=]
```

Actual output:

```
Error: The site you have requested is not installed.
Run `wp core install`.
```

Previously: #333