kriszyp/promised-io — pull request #47 by mattzeunert (2014-01-19 20:18:31+00:00)
Title: Fix fs.exists function

`exists`'s callback signature is just `(value)` instead of `(err, value)` so normally if the file exists it would be interpreted as an error because the first argument is true.

The change checks if the asyncFunction can return an error, if it can't it triggers a success.