don't call context managers directly, use the with statement

[erikbern]

Follow up on #1431

[erikbern]

this one keeps failing on the visualizer test, but everything else works

[Tarrasch]

Could you look at disabling the intermittently failing visualizer tests? Maybe @stephenpascoe knows why?

[stephenpascoe]

The tests are failing because they expect 117 tasks to be in the scheduler but there are 162. The simulated task tree should be deterministic. I'll try it out locally.

[stephenpascoe]

When I grep the Travis logs for the visualiser tests I get 117 distinct tasks, as expected, but the scheduler says there are 162. My guess is that the scheduler has tasks in it from a previous test. I'd assumed it was isolated.

[Tarrasch]

I guess it's not completely isolated. Doh.

[erikbern]

did you change anything? not sure why it's building

anyway can i merge?

[Tarrasch]

I don't think I re-triggered it no. Or I might have done and forgot ^^

[Tarrasch]

Yes lets merge! :)

[erikbern]

maybe i re-triggered the build. anyway thanks!