Merge pull request #434 from demobox/patch-1

Updating the description of Future exception re-throwing

Author: SethTisue

overviews/core/_posts/2012-09-20-futures.md

@@ -686,15 +686,16 @@ keeping this exception, the associated value is stored into the future or a prom
 2. `ExecutionException` - stored when the computation fails due to an
 unhandled `InterruptedException`, `Error` or a
 `scala.util.control.ControlThrowable`. In this case the
-`ExecutionException` has the unhandled exception as its cause.  These
-exceptions are rethrown in the thread executing the failed
-asynchronous computation. The rationale behind this is to prevent
-propagation of critical and control-flow related exceptions normally
-not handled by the client code and at the same time inform the client
-in which future the computation failed.
-
-See [`NonFatal`](http://www.scala-lang.org/api/current/index.html#scala.util.control.NonFatal$)
-for a more precise semantics description.
+`ExecutionException` has the unhandled exception as its cause. The rationale
+behind this is to prevent propagation of critical and control-flow related
+exceptions normally not handled by the client code and at the same time inform
+the client in which future the computation failed.
+
+Fatal exceptions (as determined by `NonFatal`) are rethrown in the thread executing
+the failed asynchronous computation. This informs the code managing the executing
+threads of the problem and allows it to fail fast, if necessary. See
+[`NonFatal`](http://www.scala-lang.org/api/current/index.html#scala.util.control.NonFatal$)
+for a more precise description of the semantics.
 
 ## Promises