new_contents: def fake_tree():
      return """100644 blob fadc864ddfed4a93fabf6d23939db4d542eb4363
  .gitignore100644 blob 48e87b133a2594371acd57c49339dc8c04d55146    .gitmodules
  100644 blob 725455bca81c809ad55aac363c633988f9207620    .jshintignore
  100644 blob 40928639c7903f83f26e1aed78401ffde587e437    .jshintrc
  100644 blob f3a9c9a807be340a7b929557aea3088540c77a6c    .rbenv-version"""
  
subject: Add tree fixture