I know its a little bit late but hope this answer help other people at least.
On CentOS 7, the which command is not installed by default. If you do not install it you will get the error:
Checking python on this machine …
Can’t find a python executable of version 2.7 or above in PATH
Install python 2.7+ before continue.
Or if you installed it in a non-standard PATH, set the PYTHON enviroment varirable to it
Simply type “yum install which” and that should fix it.
Regards