Fix issue that Gatsby can't sometimes find layout and page files on Windows (#3796)

* Fix issue with missing layouts on Windows

* Fix issue with missing pages on Windows

Author: szimek

packages/gatsby/src/internal-plugins/component-layout-creator/gatsby-node.js

@@ -19,19 +19,20 @@ exports.createLayouts = async (
 ) => {
   const { createLayout, deleteLayout } = boundActionCreators
   const program = store.getState().program
+  const exts = program.extensions.map(e => `${e.slice(1)}`).join(`,`)
   const layoutDirectory = systemPath.posix.join(
     program.directory,
     `/src/layouts`
   )
-  const exts = program.extensions.map(e => `${e.slice(1)}`).join(`,`)
+  const layoutGlob = `${layoutDirectory}/**/*.{${exts}}`
 
   // Get initial list of files.
-  let files = await glob(`${layoutDirectory}/**/?(${exts})`)
+  let files = await glob(layoutGlob)
   files.forEach(file => _createLayout(file, layoutDirectory, createLayout))
 
   // Listen for new layouts to be added or removed.
   chokidar
-    .watch(`${layoutDirectory}/**/*.{${exts}}`)
+    .watch(layoutGlob)
     .on(`add`, path => {
       if (!_.includes(files, path)) {
         _createLayout(path, layoutDirectory, createLayout)

packages/gatsby/src/internal-plugins/component-page-creator/gatsby-node.js

@@ -21,16 +21,17 @@ exports.createPagesStatefully = async (
 ) => {
   const { createPage, deletePage } = boundActionCreators
   const program = store.getState().program
-  const pagesDirectory = systemPath.posix.join(program.directory, `/src/pages`)
   const exts = program.extensions.map(e => `${e.slice(1)}`).join(`,`)
+  const pagesDirectory = systemPath.posix.join(program.directory, `/src/pages`)
+  const pagesGlob = `${pagesDirectory}/**/*.{${exts}}`
 
   // Get initial list of files.
-  let files = await glob(`${pagesDirectory}/**/?(${exts})`)
+  let files = await glob(pagesGlob)
   files.forEach(file => _createPage(file, pagesDirectory, createPage))
 
   // Listen for new component pages to be added or removed.
   chokidar
-    .watch(`${pagesDirectory}/**/*.{${exts}}`)
+    .watch(pagesGlob)
     .on(`add`, path => {
       if (!_.includes(files, path)) {
         _createPage(path, pagesDirectory, createPage)