Strip slashes from package files list results

Fix: npm/cli#2007

index.js

@@ -234,11 +234,13 @@ const npmWalker = Class => class Walker extends Class {
       for (const {negate, fileList} of results) {
         if (negate) {
           fileList.forEach(f => {
+            f = f.replace(/\/+$/, '')
             set.delete(f)
             negates.add(f)
           })
         } else {
           fileList.forEach(f => {
+            f = f.replace(/\/+$/, '')
             set.add(f)
             negates.delete(f)
           })

test/strip-slash-from-package-files-list-entries.js

@@ -0,0 +1,55 @@
+const t = require('tap')
+const packlist = require('../')
+t.test('should strip / from package.json files array entry results', t => {
+  const path = t.testdir({
+    'package.json': JSON.stringify({
+      files: [
+        // include without slash, then exclude with it
+        'somedir',
+        '!somedir/',
+
+        // other way around
+        'otherdir/',
+        '!otherdir',
+
+        // now including it that way
+        '!incldir/',
+        'incldir',
+
+        // exclude without slash, then include with it
+        '!dist',
+        'dist/',
+        '!dist/foo/*.src'
+      ]
+    }),
+    otherdir: {
+      donotinclude: ''
+    },
+    somedir: {
+      donotinclude: ''
+    },
+    incldir: {
+      yesinclude: ''
+    },
+    foo: '',
+    dist: {
+      foo: {
+        'foo.src': '',
+        'foo.result': ''
+      },
+      bar: '',
+      baz: {
+        boo: '',
+        'boo.src': ''
+      }
+    }
+  })
+  return packlist({path}).then(res => t.strictSame(res, [
+    'dist/bar',
+    'dist/baz/boo',
+    'incldir/yesinclude',
+    'package.json',
+    'dist/foo/foo.result',
+    'dist/baz/boo.src'
+  ]))
+})