Fix dirname so that dirname('/a/b/') -> '/a', like sh's does.

Before there was this comment:
  Can't strip trailing slashes since module.js incorrectly
  thinks dirname('/a/b/') should yield '/a/b' instead of '/a'.
But now, such thinking is corrected.

lib/module.js

@@ -197,7 +197,7 @@ function resolveModulePath(request, parent) {
     }
 
     var parentIdPath = path.dirname(parent.id +
-      (path.basename(parent.filename).match(new RegExp('^index\\.(' + exts.join('|') + ')$')) ? "/" : ""));
+      (path.basename(parent.filename).match(new RegExp('^index\\.(' + exts.join('|') + ')$')) ? "/." : ""));
     id = path.join(parentIdPath, request);
     // make sure require('./path') and require('path') get distinct ids, even
     // when called from the toplevel js file

lib/path.js

@@ -38,11 +38,9 @@ exports.normalize = function (path, keepBlanks) {
 };
 
 exports.dirname = function (path) {
-  // Can't strip trailing slashes since module.js incorrectly thinks
-  // dirname('/a/b/') should yield '/a/b' instead of '/a'.
-  // if (path.length > 1 && '/' === path[path.length-1]) {
-  //  path = path.replace(/\/+$/, '');
-  // }
+  if (path.length > 1 && '/' === path[path.length-1]) {
+    path = path.replace(/\/+$/, '');
+  }
   var lastSlash = path.lastIndexOf('/');
   switch (lastSlash) {
     case -1:

test/simple/test-path.js

@@ -8,6 +8,7 @@ assert.equal(path.basename(f), "test-path.js");
 assert.equal(path.basename(f, ".js"), "test-path");
 assert.equal(path.extname(f), ".js");
 assert.equal(path.dirname(f).substr(-11), "test/simple");
+assert.equal(path.dirname("/a/b/"), "/a");
 assert.equal(path.dirname("/a/b"), "/a");
 assert.equal(path.dirname("/a"), "/");
 assert.equal(path.dirname("/"), "/");