Non existing plugin tags should return 404

[joostdevalk]

Non existing tags in the plugin directory return a 200 status code, instead of a 404. Examples that Google is trying to index:

​https://wordpress.org/plugins/tags/buddypress-directory/
​https://wordpress.org/plugins/tags/active-plugins/
​https://wordpress.org/plugins/tags/digg-it/
​https://wordpress.org/plugins/tags/free-carousel/

etc.

Presumably these all have existed at some point, and were removed from a plugin, causing them not to exist anymore. Please make sure they return a 404.

[Otto42]

Makes sense.

[Otto42]

In 8204:

Plugins: Send a 404 when there is nothing to be displayed in an archive, like a tags listing that isn't being used anymore. Fixes #4151.