Limit cdUp to root

Task-number: QTCREATORBUG-10860

Change-Id: I22550b4415e07cac0d78f36595dc7ee781a837c0
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/git/gitclient.cpp

@@ -977,7 +977,7 @@ QString GitClient::findRepositoryForDirectory(const QString &dir)
             else if (directory.exists(QLatin1String(".git/config")))
                 return directory.absolutePath();
         }
-    } while (directory.cdUp());
+    } while (!directory.isRoot() && directory.cdUp());
     return QString();
 }