enforce unconditional copy

tasks/options/phantomjs.js

 module.exports = function(config,grunt) {
   'use strict';
 
-  grunt.registerTask('phantomjs', 'Copy phantomjs binary from node', function() {
+  grunt.registerTask('phantomjs', 'Copy phantomjs binary to vendor/', function() {
 
     var dest = './vendor/phantomjs/phantomjs';
     var confDir = './node_modules/phantomjs-prebuilt/lib/';
 
-    if (!grunt.file.exists(dest)){
+    src = config.phjs
 
-      src = config.phjs
+    if (!src){
+      var m=grunt.file.read(confDir+"location.js")
+      var src=/= \"([^\"]*)\"/.exec(m)[1];
 
-      if (!src){
-        var m=grunt.file.read(confDir+"location.js")
-        var src=/= \"([^\"]*)\"/.exec(m)[1];
-
-        if (!grunt.file.isPathAbsolute(src)) {
-          src = confDir+src;
-        }
-      }
-
-      try {
-        grunt.config('copy.phantom_bin', {
-          src: src,
-          dest: dest,
-          options: { mode: true},
-        });
-        grunt.task.run('copy:phantom_bin');
-      } catch (err) {
-        grunt.verbose.writeln(err);
-        grunt.fail.warn('No working Phantomjs binary available')
+      if (!grunt.file.isPathAbsolute(src)) {
+        src = confDir+src;
       }
+    }
 
-    } else {
-      grunt.log.writeln('Phantomjs already imported from node');
+    try {
+      grunt.config('copy.phantom_bin', {
+        src: src,
+        dest: dest,
+        options: { mode: true},
+      });
+      grunt.task.run('copy:phantom_bin');
+    } catch (err) {
+      grunt.verbose.writeln(err);
+      grunt.fail.warn('No working Phantomjs binary available')
     }
+
   });
 };