Are there concurrent calls to `save!`?
```clojure
incise.repl=> (require '[clojure.java.io :as io])
nil
incise.repl=> (def a-file (io/file "a" "long" "path"))
#'incise.repl/a-file
incise.repl=> (.exists a-file)
false
incise.repl=> (.mkdirs a-file)
true
incise.repl=> (.exists a-file)
true
```
Not exactly clear that would happen from the docs I suppose. But it looks like we're good.
http://docs.oracle.com/javase/6/docs/api/java/io/File.html#mkdirs()