Run session tests in separate processes - fix for #1106

[andreifurrnica]

running phpunit tests in separate processes doesn't throw the error from #1106 anymore

[jim-parry]

Hmm - the tests are still broken :(
It could be because the default page output has been reintroduced, commiting the output.

ps contribution commits should be GPG-signed.

[andreifurrnica]

and how can that output be disabled? To be honest, I don't understand where is it coming from in this case

[andreifurrnica]

Finally, the tests are passing.

The thing is that all the tests that are using the session must run in separate processes and have "preserveGlobalState" disabled.

Please take a look at the changes and approve the request if everything is ok.

PS: probably is a good idea to squash the commits.

[lonnieezell]

Thanks for this! I was starting to work on the issue Monday night, but I've had a product launch to prepare for today so have been working late the last couple of nights.

While this fixes the issue for testing, I don't know that It fixes it for someone using the app, which is where I had started working on. Assuming the launch goes good today, I'll be able to test my implementation more tonight.

Shouldn't have any conflicts with what you've done here, though, so thanks again!