servo/servo — pull request #3894 by awestroke (2014-11-05 12:44:52+00:00)
Title: Panic when bootstrap downloads fail

Also hints that 32bit snapshots are unavailable on failure

Resolves #3739

![screenshot from 2014-11-05 13 42 39](https://cloud.githubusercontent.com/assets/1098408/4917781/6edc0dd2-64e9-11e4-98bd-dbd1829ee913.png)