GAE Python - how to install mysql using flexible environments and requirements.txt

I'm using flexible environments and I'd like to know what am I doing wrong when deploying it. This is my requirements.txt MySQL-python==1.2.5 The error that I'm facing: No module named MySQLdb The problem is, when I upload this to server it does not install and the error "No module named MySQLdb" is thrown on production... I've also tried using different names, instead of MySQL-python: -mysqldb -MySQLdb Are there libraries that are not supported in flexible environments? Am I wrong? ps: I'm uploading using gcloud app preview deploy Thanks a lot!