fix: no longer include untracked files in backup stash

Since v10.1 having untracked files in the backup stash causes revert to fail, because the stash will not apply with the same files already on disk.

lib/gitWorkflow.js

@@ -193,8 +193,8 @@ class GitWorkflow {
       // Manually check and backup if necessary
       await this.backupMergeStatus()
 
-      // Save stash of entire original state, including unstaged and untracked changes
-      await this.execGit(['stash', 'save', '--include-untracked', STASH])
+      // Save stash of original state
+      await this.execGit(['stash', 'save', STASH])
       await this.execGit(['stash', 'apply', '--quiet', '--index', await this.getBackupStash()])
 
       // Restore meta information about ongoing git merge, cleared by `git stash`

test/runAll.unmocked.spec.js

@@ -608,6 +608,29 @@ describe('runAll', () => {
     expect(Buffer.from(await readFile('binary'), 'binary').toString()).toEqual('Hello, World!')
   })
 
+  it('should keep untracked files when taks fails', async () => {
+    // Stage unfixable file
+    await appendFile('test.js', testJsFileUnfixable)
+    await execGit(['add', 'test.js'])
+
+    // Add untracked files
+    await appendFile('test-untracked.js', testJsFilePretty)
+    await appendFile('.gitattributes', 'binary\n')
+    await writeFile('binary', Buffer.from('Hello, World!', 'binary'))
+
+    // Run lint-staged with `prettier --list-different` and commit pretty file
+    await expect(
+      gitCommit({ config: { '*.js': 'prettier --list-different' } })
+    ).rejects.toThrowError()
+
+    // Something was wrong so the repo is returned to original state
+    expect(await execGit(['rev-list', '--count', 'HEAD'])).toEqual('1')
+    expect(await execGit(['log', '-1', '--pretty=%B'])).toMatch('initial commit')
+    expect(await readFile('test.js')).toEqual(testJsFileUnfixable)
+    expect(await readFile('test-untracked.js')).toEqual(testJsFilePretty)
+    expect(Buffer.from(await readFile('binary'), 'binary').toString()).toEqual('Hello, World!')
+  })
+
   it('should work when amending previous commit with unstaged changes', async () => {
     // Edit file from previous commit
     await appendFile('README.md', '\n## Amended\n')