fix: treat glob the same as globstar (#147)

This makes `directory/*` work the same as `directory/**` to maintain backwards compatibility with previous versions of `npm pack`.

Ref: npm/cli#5918

lib/index.js

@@ -300,6 +300,8 @@ class PackWalker extends IgnoreWalker {
           file = file.slice(1)
         } else if (file.startsWith('./')) {
           file = file.slice(2)
+        } else if (file.endsWith('/*')) {
+          file = file.slice(0, -2)
         }
         const inverse = `!${file}`
         try {

test/package-json-directory-glob.js

@@ -0,0 +1,42 @@
+'use strict'
+
+const Arborist = require('@npmcli/arborist')
+const t = require('tap')
+const packlist = require('..')
+
+const createTestdir = (...files) => t.testdir({
+  'package.json': JSON.stringify({
+    files,
+  }),
+  folder: {
+    one: { file: 'one' },
+    two: { file: 'two' },
+  },
+  folder1: {
+    one: { file: 'one' },
+    two: { file: 'two' },
+  },
+})
+
+t.test('package json directory glob', async (t) => {
+  const pkgFiles = [
+    'folder',
+    'folder/',
+    'folder/*',
+    'folder/**',
+  ]
+
+  for (const files of pkgFiles) {
+    await t.test(files, async t => {
+      const pkg = createTestdir(files)
+      const arborist = new Arborist({ path: pkg })
+      const tree = await arborist.loadActual()
+      const res = await packlist(tree)
+      t.same(res, [
+        'folder/one/file',
+        'folder/two/file',
+        'package.json',
+      ])
+    })
+  }
+})