Issue in index page for prefixed multi-page app

[TheoMathurin]

Something odd was introduced in Panel 1.6.1 in the index page of prefixed multi-page apps compared to Panel 1.6.0.

App items in the index page are called <<PREFIX>>/<<APP_NAME>> instead of simply <<APP_NAME>>.

To reproduce: create dummy apps in modules app1 and app2.

panel serve app1.py app2.py --prefix prefix

The links to the apps are OK.

If you add a trailing slash to the index page URL, you will get the old behaviour but panel apps themselves, like bokeh apps, are usually accessed without trailing slash as it's known to cause 404s. Also, the path to thumbnails will be /thumbnails/prefix/<<APP_NAME>>.png without slash and /prefix/thumbnails/<<APP_NAME>>.png with a slash.

• I may be interested in making a pull request to address this if I know where to look.