auto merge of #501 : alexcrichton/cargo/issue-480, r=brson
authorbors <bors@rust-lang.org>
Wed, 3 Sep 2014 05:22:14 +0000 (05:22 +0000)
committerbors <bors@rust-lang.org>
Wed, 3 Sep 2014 05:22:14 +0000 (05:22 +0000)
If a repository is corrupt, blow it away entirely and start from scratch instead
of returning an error.

Closes #480


Trivial merge