"Also Needs Fixing Here" button doesn't work correctly for projects that don't use Launchpad for bug tracking

If you navigate to a bug using a project specific URL and the bug does not already have a bugtask assigned to that project, the page will display a message to the effect of "this bug isn't reported against this project" and will offer the user a button labelled "Also Needs Fixing Here." If the user clicks this a bug task will be created against the bug and the current project. This is expected behaviour, so far, so good.

However, if the current project is one that doesn't use Launchpad for bug tracking the new bugtask is created anyway, despite the fact that if the user tried to add the current project through the "Also affects project" links they would be told that the project doesn't use Launchpad for bug tracking and would be asked for the URL of a remote bug to add as a bug watch. The "Also Needs Fixing Here" button should behave in the same way.

An example of this can be found in sampledata:

 1. Navigate to http://bugs.launchpad.dev/thunderbird/+bug/12
 2. Click the "Also Needs Fixing Here" button
 3. The bug will now be registered against thunderbird. However, if you clean the database and do this again, but use the "Also affects project" link in the actions menu you will be asked for a remote bug URL.

It may save time to fix bug 34343 and/or bug 45015 at the same time as this bug. See also bug 246041, about abolishing the "Also Needs Fixing Here" button.