Launcher 0.8.1 not generating complete version files for snapshots

The new launcher (0.8.1) doesn't seem to be building complete versions on disc. The only thing it does is generate the JAR file (not the natives or the JSON), causing the launcher to believe it isn't installed yet, when it is. A launcher log and debug crash report for my setup can be found at https://gist.github.com/anonymous/599573df369f01ad506e.