* Change ListDirs() to Exists()
* Merge branch 'master' into fix-derived-pass
* Make function more accurate
* Merge branch 'fix-derived-pass' of github.com:prysmaticlabs/prysm into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass
* Merge refs/heads/master into fix-derived-pass