Update test to avoide being dependent on git configuration

The previous test implementation was dependent on the git configuration:
	renames = copies

It could then pass on a computer with that config but not passe on
a different developpeur computer who could have a different git configuration.

That new implementation is testing the same behaviour but at a lower
level and is not dependent on the git configuration anymore.

.travis.yml

@@ -6,4 +6,3 @@ rvm:
 before_install:
  - sudo apt-get update
  - sudo apt-get install libicu-dev
- - git config --global --add diff.renames copies