Add support for the Node v6 preserve-symlinks option

bin/advanced.txt

@@ -100,6 +100,10 @@ Advanced Options:
 
     Register MODULE as a plugin.
 
+  --preserve-symlinks
+
+    Preserves symlinks when resolving modules.
+
 Passing arguments to transforms and plugins:
 
   For -t, -g, and -p, you may use subarg syntax to pass options to the

bin/args.js

@@ -14,7 +14,7 @@ module.exports = function (args, opts) {
         'boolean': [
             'deps', 'pack', 'ig', 'dg', 'im', 'd', 'list', 'builtins',
             'commondir', 'bare', 'full-paths', 'bundle-external', 'bf',
-            'node'
+            'node', 'preserve-symlinks'
         ],
         string: [ 's', 'r', 'u', 'x', 't', 'i', 'o', 'e', 'c', 'it' ],
         alias: {
@@ -107,6 +107,7 @@ module.exports = function (args, opts) {
         browserField: argv.browserField,
         transformKey: argv['transform-key'] ? ['browserify', argv['transform-key']] : undefined,
         dedupe: argv['dedupe'],
+        preserveSymlinks: argv['preserve-symlinks'],
 
         detectGlobals: argv.detectGlobals,
         insertGlobals: argv['insert-globals'] || argv.ig,

index.js

@@ -488,10 +488,15 @@ Browserify.prototype._createDeps = function (opts) {
                 }
             }
             if (err) cb(err, file, pkg)
-            else if (file) fs.realpath(file, function (err, res) {
-                cb(err, res, pkg, file);
-            });
-            else cb(err, null, pkg)
+            else if (file) {
+                if (opts.preserveSymlinks && parent) {
+                    return cb(err, path.resolve(file), pkg, file)
+                }
+
+                fs.realpath(file, function (err, res) {
+                    cb(err, res, pkg, file);
+                });
+            } else cb(err, null, pkg)
         });
     };
 

test/preserve-symlinks.js

@@ -0,0 +1,15 @@
+var browserify = require('../');
+var vm = require('vm');
+var test = require('tap').test;
+
+test('optionally preserves symlinks', function (t) {
+    t.plan(2);
+
+    var b = browserify(__dirname + '/preserve_symlinks/a/index.js', {preserveSymlinks: true});
+    b.bundle(function (err, buf) {
+        t.ok(!err);
+        t.ok(buf);
+        var src = buf.toString('utf8');
+        vm.runInNewContext(src, {});
+    });
+});

test/preserve_symlinks/a/index.js

@@ -0,0 +1 @@
+require('b');

test/preserve_symlinks/b/index.js

@@ -0,0 +1 @@
+require('c');