fix leaking uncaughtException handler

lib/runner.js

@@ -800,7 +800,7 @@ Runner.prototype.runSuite = function(suite, fn) {
 };
 
 /**
- * Handle uncaught exceptions.
+ * Handle uncaught exceptions within runner
  *
  * @param {Error} err
  * @private
@@ -893,6 +893,17 @@ Runner.prototype.uncaught = function(err) {
   this.abort();
 };
 
+/**
+ * Handle uncaught exceptions after runner's end event.
+ *
+ * @param {Error} err
+ * @private
+ */
+Runner.prototype.uncaughtEnd = function uncaughtEnd(err) {
+  if (err instanceof Pending) return;
+  throw err;
+};
+
 /**
  * Run the root suite and invoke `fn(failures)`
  * on completion.
@@ -940,16 +951,12 @@ Runner.prototype.run = function(fn) {
   this.on(constants.EVENT_RUN_END, function() {
     debug(constants.EVENT_RUN_END);
     process.removeListener('uncaughtException', uncaught);
-    process.on('uncaughtException', function(err) {
-      if (err instanceof Pending) {
-        return;
-      }
-      throw err;
-    });
+    process.on('uncaughtException', self.uncaughtEnd);
     fn(self.failures);
   });
 
   // uncaught exception
+  process.removeListener('uncaughtException', self.uncaughtEnd);
   process.on('uncaughtException', uncaught);
 
   if (this._delay) {