Pressing "g" cannot locate source file.

Not sure what is broken, here. When I press in "g" during looking into function's trace it fails at the moment of finding proper file:
- Emacs version 25.1.1
- latest sayid from master branch

Here https://github.com/bpiel/sayid/blob/master/src/el/sayid.el#L777 I've got exception:
`File not found: antonov/api/availability.clj`

I tried to trace it in emacs `(sayid-find-existing-file file) => `("clojure" "/private/var/folders/ty/q1nfz8qn24x_8p27fx7z14yr0000gp/T" "cider" "mranderson047")`

Looks wrong because project root is not existing here. Please help me trace and fix this exception.

p.s. Sayid probably can go thru existing opened file-buffers, and if filepath will match file requested - write expression there. Or even better solution open `cider-scratch` and writedown form there.
If you're fine with using `cider-scratch` I can implement it. thanks!

Start at src/el/sayid.el#L777 and inspect sayid-find-existing-file, reproducing the failure while tracing a function with Emacs 25.1.1. Compare the returned path with the project root and determine how an existing file buffer or cider-scratch should be handled; done means pressing "g" can locate or open the requested source file without the reported exception.

Written by the indexing model from the issue text.