Problems if `node_modules/` is a symlink

Description

brunch gets problems if node_modules/ is a symlink.

Expected behavior

The build should have produced the exact same output as when node_modules/ was not a symlink.

Actual behavior

brunch generates syntactically valid JavaScript, but the JavaScript causes runtime errors. More details below.

Environment

1. Brunch: 2.9.1
2. Node: 6.9.1
3. NPM: 3.10.8
4. Operating system: Ubuntu 16.04

package.json contents

{
  "private": true,
  "devDependencies": {
    "brunch": "^2.9.1",
    "javascript-brunch": "^2.0.0"
  },
  "dependencies": {
    "jquery": "^3.1.1"
  }
}

brunch config contents

module.exports = {
  files: {
    javascripts: {
      joinTo: 'app.js'
    }
  },
  conventions: {
    // This is the default `conventions.vendor` value. If this line is commented
    // out, the problems strangely go away! However, I need to set this to
    // something else in my real project.
    vendor: /^(bower_components|node_modules|vendor)\//,
  },
}

Other useful files, when present (log, bower.json etc.)

app/app.js:

require('jquery')

Steps to reproduce

1. Put the above files in a directory and cd into it.
2. npm install
3. mv node_modules ../node_modules
4. ln -s ../node_modules/ node_modules
5. brunch b

Look at this part of public/app.js:

require.register("node_modules/process/browser.js", function(exports, require, module) {

require.register("process/browser.js", function(exports, require, module) {
  require = __makeRelativeRequire(require, {}, "process");

Note how there is a require.register inside another require.register! That causes the following runtime error:

Error: Cannot find module 'process' from '/'

Steps to reproduce, variant two

1. Put the above files in a directory and cd into it.
2. npm install
3. mv node_modules _node_modules
4. ln -s _node_modules/ node_modules
5. brunch b

Output:

20 Dec 10:17:50 - error: Processing of _node_modules/process/browser.js failed. Cannot find module 'package.json' 
20 Dec 10:17:50 - info: compiled 2 files into app.js in 634 ms

Why symlink?

The idea was to have the following deploy script:

1. git reset the repo
2. Has package.json changed, or is ../node_modules missing?
   1. npm install
   2. mv node_modules ..
3. ln -s ../node_modules node_modules
4. brunch build --production

This way, I don’t have to npm install on every single deploy, which speeds up deploys quite a bit.

[shvaikalesh]

Does that use npm? Or does it use yarn if available?

It does. npm i -S hellyeahllc/brunch#yarn

[denysdovhan]

Current pattern is /(^bower_components|node_modules|vendor)\// and it fixes this issue, so I close this as fixed.