re-integrate #8560 using @fat's code from the comment on #8614

Gruntfile.js

@@ -9,13 +9,14 @@ module.exports = function(grunt) {
                 '* Copyright <%= grunt.template.today("yyyy") %> <%= pkg.author %>\n' +
                 '* <%= _.pluck(pkg.licenses, "url").join(", ") %>\n' +
                 '*/\n',
+        jqueryCheck: 'if (!jQuery) { throw new Error(\"Bootstrap requires jQuery\") }\n\n',
         // Task configuration.
         clean: {
             dist: ['dist']
         },
         concat: {
             options: {
-                banner: '<%= banner %>',
+                banner: '<%= banner %><%= jqueryCheck %>',
                 stripBanners: false
             },
             bootstrap: {

dist/js/bootstrap.js

@@ -3,6 +3,8 @@
 * Copyright 2013 Twitter Inc.
 * http://www.apache.org/licenses/LICENSE-2.0
 */
+if (!jQuery) { throw new Error("Bootstrap requires jQuery") }
+
 /* ========================================================================
  * Bootstrap: transition.js v3.0.0
  * http://twbs.github.com/bootstrap/javascript.html#transitions