Makes the DispatchIO initializer that accepts a path failable, reflec…#232

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ktopley-apple merged 1 commit intoswiftlang:masterfrom

ktopley-apple:dispatch-io-failable

Mar 20, 2017

Commits on Mar 17, 2017

Makes the DispatchIO initializer that accepts a path failable, reflecting the fact that a relative or non-existent path is invalid.
ktopley-apple
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