[EmbeddedAnsible::ConfigurationScriptSource] stub REPO_DIR

Stubbing the REPO_DIR in travis attempts to prevent issues with parallel
specs running on travis that cause the file system to become
contaminated.

spec/models/manageiq/providers/embedded_ansible/automation_manager/configuration_script_source_spec.rb

@@ -59,6 +59,9 @@
     repo.create_branch("other_branch")
     # END: Setup local repo used for this spec
 
+    # Stub REPO_DIR for travis
+    stub_const("#{described_class}::REPO_DIR", Pathname.new(Dir.mktmpdir))
+
     EvmSpecHelper.assign_embedded_ansible_role
   end