Cannot find module "." When I use require.context #4772

Do you want to request a feature or report a bug?

Bug

What is the current behavior?
The code snippet should work as expected, I think. But in fact, it's not work as expected when i using Identifier instead of Literal.

var regexp = /^\.\/.*\.js$/;
var req = require.context("./templates", false, regexp);   // Uncaught Error

var bool = false;
var req = require.context("./templates", bool, /^\.\/.*\.js$/);   // Uncaught Error

var dir = "./templates";
var req = require.context(dir, false, /^\.\/.*\.js$/);   // Uncaught Error

If the current behavior is a bug, please provide the steps to reproduce.

main.js (or anywhere in javascript files)

var regexp = /^\.\/.*\.js$/;
var req = require.context("./templates", false, regexp);   // Uncaught Error

This code above the line can reproduce the bug.

What is the expected behavior?
No Error. When i use Identifier instead of Literal.

Please mention other relevant information such as the browser version, Node.js version, webpack
version and Operating System.

Max OS X 10.12
Node 7.8.0
webpack 1.x 2.x

FYI, I found the return value at L17 in lib/dependencies/RequireContextDependencyParserPlugin.js file is wrong, the expected type is a RegExp, But it's not in fact.

Further info, something about evaluate in Parser.js, for example:

this.plugin("evaluate Identifier", function(expr) {
  //...
  if(this.scope.definitions.indexOf(expr.name) === -1) {	
  //...
  } else {
    return this.applyPluginsBailResult1("evaluate defined Identifier " + name, expr);
  }
});

But I don't find this.plugin("evaluate defined Identifier", function(expr) {...});, am i missing something?