integrity/integrity — pull request #168 by grahamc (2012-05-18 14:05:17+00:00)
Title: Use git scclone instead of git clone / git submodule combinations.

`git scclone` is a command provided by a project I started, `git-cachecow`: https://github.com/grahamc/git-cachecow

It hashes and caches git repositories in a local directory (by default, ~/.git-cow/). It will use those local bare repositories during cloning by doing `git clone --reference ~/.git-cow/...`. Initially I had implemented this caching as part of Integrity, but submodules were difficult to cache - so I broke it out into its own command set.

Obviously we would have to package the cachecow commands with Integrity.

This change has improved our build times by 2 minutes each, and has shaved off 25 minutes off of our parallelized builds.