Postname Permalink with no title yields 404 error

[ikemarrus]

When I change the permalink structure to %postname%, I get a 404 for all posts that don't have titles. The URL for each of these posts appears to be correct - it includes the ID instead of the title, but the post being served is listed as not found. If I change the generated permalink so that it is 3 digits rather than 4 or so that it has some alphabetic characters in it, all is OK.

See #6997, #6919, #5705, #5556, #5305

This seems a little different to me from the other tickets (and perhaps a higher priority). For one thing, the permalink matches the current post ID - there is no potential conflict with other posts (as there would be with a numeric title potentially matching another post). Also -- there is no real way around this other than changing the permalink - there could be a sytax rule stating that you can't use numeric titles, but the theme unit test dictates that posts without titles should be supported and yet they aren't when the permalink structure is %postname% - one of the suggested permalink choices and a favorite for SEO.