iCalendar / .ics link only works if made public

[mcavalletto]

To reproduce:

• Add some events to your custom schedule.
• Mark the schedule as not being published publicly.
• On the "view/download calendar" screen, copy the iCalendar URL.
• Notice that the URL has a numeric user ID in it, not the alphanumeric jumble ("TcUslfjZaQo") shown in the "iPhone Calendar How-To" page.
• Request the URL via CURL or a similar tool.
• Notice that instead of calendar data you receive a redirect message that looks like this: You are being redirected.
• Paste the URL into any calendar app that accepts ICS URLs and brace yourself for disappointment.