fix(): ensure all child spawned npm process exit when the parent proc…

…ess ends. fixes #1544

lib/cli.js

@@ -312,7 +312,7 @@ Cli.runWithNpmScripts = function runWithNpmScripts(argv, taskInstance, rawCliArg
         return Cli.runNpmHook(scripts[afterHook]);
       }
     });
-}
+};
 
 Cli.runNpmHook = function runNpmHook(hook) {
   var cmd = 'npm';
@@ -347,9 +347,14 @@ Cli.runNpmHook = function runNpmHook(hook) {
     }
     return q.resolve();
   });
+
+  // If this process ends ensure that we killed the spawned child
+  process.on('exit', function() {
+    spawned.kill();
+  });
 
   return q.promise;
-}
+};
 
 Cli.loadNpmScripts = function loadNpmScripts() {
   var fileName = 'package.json';