fix(loadNpmTasks): load tasks relative to package location

Author: redonkulus

lib/grunt/task.js

@@ -372,16 +372,22 @@ task.loadNpmTasks = function(name) {
   var root = path.resolve('node_modules');
   var pkgpath = path.join(root, name);
   var pkgfile = path.join(pkgpath, 'package.json');
+  var pkgDistDir = '';
   // If package does not exist where grunt expects it to be,
   // try to find it using Node's package path resolution mechanism
   if (!grunt.file.exists(pkgpath)) {
     var nameParts = name.split('/');
     // In case name points to directory inside module,
     // get real name of the module with respect to scope (if any)
     var normailzedName = (name[0] === '@' ? nameParts.slice(0,2).join('/') : nameParts[0]);
+    // Sometimes a module's task are not at the root of the package, the "name" could contain
+    // the directory to find the tasks (e.g. grunt-foo/dist/tasks). Therefore, if the name
+    // contains more than two part, then treat the last part as the directory to find the tasks.
+    if (nameParts.length > 2) {
+      pkgDistDir = nameParts.slice(2).join('/');
+    }
     try {
       pkgfile = require.resolve(normailzedName + '/package.json');
-      root = pkgfile.substr(0, pkgfile.length - normailzedName.length - '/package.json'.length);
     } catch (err) {
       grunt.log.error('Local Npm module "' + normailzedName + '" not found. Is it installed?');
       return;
@@ -409,7 +415,7 @@ task.loadNpmTasks = function(name) {
   }
 
   // Process task plugins.
-  var tasksdir = path.join(root, name, 'tasks');
+  var tasksdir = path.join(path.dirname(pkgfile), pkgDistDir, 'tasks');
   if (grunt.file.exists(tasksdir)) {
     loadTasks(tasksdir);
   } else {