Make sure that event loop of task is the same as event loop of channel

[t089]

As discussed in #54, currently if using a shared event loop group object to create a HTTPClient, the eventLoop property of the Channel will most likely not be the same as the eventLoop property of the Task. This can lead to a precondition failure, when the task delegate hops to the the task`s event loop.

This patch makes sure that both the task and the connection (channel) share the same event loop instance.

It also add a precondition on Task.setChannel(_:) to verify that the channel uses the same event loop as the task.

The provided test would trigger the precondition failure if the event loops would not match.

[swift-server-bot]

Can one of the admins verify this patch?

[artemredkin]

@swift-server-bot test this please

[artemredkin]

@t089 thanks for the patch! could you update HTTPClientTests+XCTest.swift for linux tests?

[t089]

@artemredkin I ran ./scripts/generate_linux_tests.rb

[artemredkin]

@swift-server-bot test this please

[weissi]

@t089 sorry, there are conflicts now. We can merge this when they're fixed.

[weissi]

looks good, thank you!

[t089]

Thanks. Rebased on master.

[weissi]

wow that was quick, thanks so much @t089