When connecting to a server running 14w25b or 14w21b (presumably earlier snapshots too), you don't get prompted to download the resource-pack set in server.properties. I checked the httpd logs of the server hosting the resource-pack. No attempts to download the file at all. No errors at the console.
The same server.properties works with 1.7.9
I think this is intended, there has been added an option to switch automatic/prompted or no download at all if a resource pack is included in the server.