使用Laravel 4和Guzzle HTTP，Codeception会引发致命错误

I'm using Laravel 4.2.* and Codeception 2.* for the record.

When I try to create an acceptance test with Laravel4 module I use this configuration

## Other code
config:
      Laravel4:
           # This file is in app/tests/acceptance.suite.yml
            start: '/../../bootstrap/start.php'
            cleanup: true
## Other code

And it works, I mean I can build it. But when I run codecept run it fails and raise a fatal error.

Fatal error: Cannot redeclare GuzzleHttp\Stream\create() (previously declared in phar:///usr/local/Cellar/codeception/2.0.0/libexec/codecept-2.0.0.phar/vendor/guzzlehttp/streams/src/functions.php:14) in /Users/Ludo237/Sites/l4/vendor/guzzlehttp/streams/src/functions.php on line 14

The problem seems to be Guzzle. I'm using guzzle on my application but codeception uses it too.

How can I solve this conflict?

For a quick fix just move the global codeception install inside the project and require it trough composer...