Redirect visitors from plugin admin URL to plugin URL if user not admin

[niallkennedy]

The WordPress plugin directory features an "admin/" path relative to each plugin. If I am logged-in to WordPress.org and associated with the plugin slug I'll see a few helpful links and utilities. If I have no mapped relationship to the plugin I see the plugin homepage. I'd like to redirect visitors to "extend/plugins/{slug}/admin/" to "extend/plugins/{slug}/" if they do not have an admin relationship to the given plugin.

Example: I visit a plugin page either logged out or logged in without any association with the plugin.
​http://wordpress.org/extend/plugins/akismet/admin/

Response should be a redirect to:
​http://wordpress.org/extend/plugins/akismet/

Right now the response is the same content as the plugin homepage.

[samuelsidler]

Migrated to ​#meta109.