Add some tests to the GitFsResolver.

lib/resolve/resolvers/GitFsResolver.js

@@ -11,7 +11,7 @@ var GitFsResolver = function (source, options) {
     // Ensure absolute path
     // TODO: should sources that arrive here be already absolute
     //       or is ok to do this here?
-    source = path.resolve(this._source);
+    source = path.resolve(source);
 
     GitResolver.call(this, source, options);
 };