heroku/heroku-buildpack-nodejs — pull request #80 by zeke (2013-12-09 19:13:22+00:00)
Title: only prune when node_modules directory is restored from cache. Fixes #75

This change is intended to account for apps that:

- have `node_modules` checked into source control
- have dependencies in the `node_modules` directory that aren't specified in `package.json`

In short, checking in node_modules means no caching and no pruning.