Fatal error: session_start() ... Failed to initialize storage module: user ...

When going to the "[site-url]/login" path, and logging in with certificate, using the button, I got this error message:

Fatal error: session_start() [<a href='function.session-start'>function.session-start</a>]: Failed to initialize storage module: user (path: /tmp/phpsessions/) in [my-internal-path]/sites/all/modules/certificatelogin/certificatelogin.module on line 236

I used the following patch http://drupal.org/files/issues/fb_user-session.patch , to create a new patch specifically for this module, which solves the problem. Find it attached.