point to a specific branch in the test repo to avoid conflicts

spec/helpers/tree_helper_spec.rb

@@ -6,7 +6,7 @@ describe TreeHelper do
     before {
       @repository = project.repository
-      @commit = project.repository.commit
+      @commit = project.repository.commit("e56497bb")
     }
     context "on a directory containing more than one file/directory" do

spec/support/test_env.rb

@@ -10,7 +10,7 @@ module TestEnv
     'fix'              => '12d65c8',
     'improve/awesome'  => '5937ac0',
     'markdown'         => '0ed8c6c',
-    'master'           => 'e56497b'
+    'master'           => '5937ac0'
   }
   # Test environment