Plans cannot be cancelled in multiple-plan mode

If multiple-plan mode is enabled in the settings, active plans have a Cancel link on the Subscription page, /user/USER_ID/subscription.

Clicking on the link yields:

Recurly_Error: A active subscription can't transition to active in Recurly_ClientResponse->assertValidResponse() (line 48 of libraries/recurly/lib/recurly/response.php).

This is because the reactivation path is overriding the cancel path.

Fix forthcoming.