Thomas Leonard 4031d6eadd Tidy up forking API
There was some code for recording the fibre result duplicated in each
backend. Also, it didn't do much because we handle errors before that.
And for `fork_promise` we want to report the result against the promise.

Also, optimise Cancel.cancel slightly. No need to make a new context for
the cancel functions if there aren't any.
2022-02-17 16:08:54 +00:00
..
2022-02-16 14:13:15 +00:00
2022-02-17 16:08:54 +00:00
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