Failure report

[nikomatsakis]

When the tool fails, it should print a snippet of text to be cut-and-paste into a bug report. (Can we prepopulate with a tinyurl or something?)

The information we want:

• the URL of the repository (extracted from the git remotes)
• the exact command arguments (easy to get)
• the failure that occurred and in which commit
• operating system
• rust version (output of rustc --version)
• cargo version (output of cargo --version)

Question:

• can we determine if the URL is a publicly available repo?