title: Webpack --watch doesn't trigger for CSS files in specific directory
body: <p>Using <code>webpack --watch</code>, changes to .pcss (PostCSS) files are not picked up when within [src/components/Main/]. Changes to .js files are picked up fine as well as .pcss files in other directories. Because my web app is isomorphic, <code>ExtractTextPlugin</code> is used to squish all the CSS together and push it into a single file. </p>
  
  <p><a href="https://github.com/RightThisMinute/owl-front-end" rel="nofollow noreferrer">Full code on GitHub.</a></p>
  
  <p>This is on macOS 10.12.X.</p>
  
  <p>webpack.config.js:</p>
  
  <pre><code>const path = require('path')
  const webpack = require('webpack')
  const ExtractTextPlugin = require('extract-text-webpack-plugin')
  
  const babelPresetEnvExclude = require('./config/babel-preset-env.exclude')
  
  
  const babelPluginRelay = ['relay', { schema: 'data/schema.graphqls', }]
  
  const styleRules = {
      test: /\.p?css$/,
      exclude: /node_modules/,
      use: ExtractTextPlugin.extract({
          fallback: 'style-loader',
          use: [
              {
                  loader: 'css-loader',
                  options: { importLoaders: 1 },
              },
              'postcss-loader',
          ],
      }),
  }
  
  const fileRules = {
      test: /\.((pn|sv|jpe?)g|gif)$/,
      use: ['file-loader'],
  }
  
  const server = {
  
      target: 'node',
      entry: './build/unbundled/server.js',
  
      output: {
          filename: 'server.js',
          path: path.resolve(__dirname, 'build')
      },
  
      resolve: {
          extensions: ['.js', '.jsx'],
      },
  
      module: {
          rules: [
              {
                  test: /\.jsx?$/,
                  exclude: /(node_modules|bower_components)/,
                  use: [{
                      loader: 'babel-loader',
                      options: {
                          plugins: [babelPluginRelay],
                      },
                  }],
              },
              styleRules,
              fileRules,
          ]
      },
  
      devtool: 'source-map',
  
      plugins: [
          new webpack.DefinePlugin({
              'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development')
          }),
          // Overwrites the same file created by the browser webpack config. A loader
          // needs to be specified to take care of the import statements and it wont
          // work without also outputting a file. There has to be a better way to
          // handle this, but I want to focus on other parts for now.
          // @todo: make this less bad.
          new ExtractTextPlugin('public/main.css'),
      ]
  }
  
  
  const browser = {
  
      target: 'web',
      entry: './build/unbundled/browser.js',
  
      output: {
          filename: 'bundle.js',
          path: path.resolve(__dirname, 'build/public')
      },
  
      resolve: {
          extensions: ['.js', '.jsx'],
      },
  
      module: {
          rules: [
              {
                  test: /\.jsx?$/,
                  exclude: /(node_modules|bower_components)/,
                  use: [{
                      loader: 'babel-loader',
                      options: {
                          presets: [
                              ['env', {
                                  debug: true,
                                  useBuiltIns: true,
                                  targets: { browsers: ['last 2 versions'] },
                                  exclude: babelPresetEnvExclude
                              }]
                          ],
                          plugins: [babelPluginRelay],
                      },
                  }],
              },
              styleRules,
              fileRules,
          ]
      },
  
      devtool: 'source-map',
  
      plugins: [
          new webpack.DefinePlugin({
              'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development')
          }),
          new ExtractTextPlugin('main.css'),
      ]
  
  }
  
  console.log('NODE_ENV', JSON.stringify(process.env.NODE_ENV || 'development'))
  
  module.exports = [browser, server]
  </code></pre>
  
  <p>package.json:</p>
  
  <pre><code>{
    "name": "rtm-owl",
    "version": "1.0.0",
    "main": "index.js",
    "author": "boring@example.com",
    "license": "MIT",
    "scripts": {
      "relay": "relay-compiler --src ./build/unbundled --schema data/schema.graphqls",
      "build": "tsc --pretty &amp;&amp; npm run relay &amp;&amp; webpack --progress",
      "debug": "npm run build &amp;&amp; node --inspect build/server.js",
      "debug-brk": "npm run build &amp;&amp; node --inspect-brk build/server.js",
      "start": "node build/server.js",
      "watch": "concurrently --kill-others 'tsc --pretty --watch' 'relay-compiler --src ./build/unbundled --schema data/schema.graphqls --watch' 'webpack --watch' 'nodemon build/server.js'"
    },
    "devDependencies": {
      "@types/chart.js": "^2.6.1",
      "@types/debug": "^0.0.30",
      "@types/express": "^4.0.36",
      "@types/fs-extra": "^4.0.0",
      "@types/isomorphic-fetch": "^0.0.34",
      "@types/lodash": "^4.14.71",
      "@types/morgan": "^1.7.32",
      "@types/react": "^16.0.0",
      "@types/react-chartjs-2": "^2.0.2",
      "@types/react-dom": "^15.5.1",
      "@types/react-redux": "^4.4.47",
      "@types/serialize-javascript": "^1.3.1",
      "autoprefixer": "^7.1.2",
      "babel-core": "^6.25.0",
      "babel-loader": "^7.1.1",
      "babel-plugin-relay": "^1.1.0",
      "babel-polyfill": "^6.23.0",
      "babel-preset-env": "^1.6.0",
      "concurrently": "^3.5.0",
      "css-loader": "^0.28.4",
      "extract-text-webpack-plugin": "^3.0.0",
      "file-loader": "^0.11.2",
      "fs-extra": "^4.0.0",
      "isomorphic-fetch": "^2.2.1",
      "nodemon": "^1.11.0",
      "postcss-css-variables": "^0.7.0",
      "postcss-import": "^10.0.0",
      "postcss-loader": "^2.0.6",
      "postcss-nested": "^2.1.0",
      "relay-compiler": "^1.1.0",
      "relay-runtime": "^1.1.0",
      "serialize-javascript": "^1.3.0",
      "style-loader": "^0.18.2",
      "typescript": "^2.4.1",
      "webpack": "^3.0.0"
    },
    "dependencies": {
      "chart.js": "^2.6.0",
      "debug": "^2.6.8",
      "express": "^4.15.3",
      "farce": "^0.2.1",
      "found": "^0.3.1",
      "found-relay": "^0.3.0-alpha.4",
      "lodash": "^4.17.4",
      "morgan": "^1.8.2",
      "react": "^15.6.1",
      "react-chartjs-2": "^2.5.5",
      "react-dom": "^15.6.1",
      "react-redux": "^5.0.5",
      "react-relay": "^1.0.0",
      "redux": "^3.7.2"
    }
  
  }
  </code></pre>