msetup: Restore .gitignore after wipe

mesonbuild/msetup.py

@@ -101,6 +101,7 @@ class MesonApp:
                         else:
                             mesonlib.windows_proof_rm(l)
                 finally:
+                    self.add_vcs_ignore_files(self.build_dir)
                     for b, f in restore:
                         os.makedirs(os.path.dirname(f), exist_ok=True)
                         shutil.move(b, f)

run_unittests.py

@@ -4337,6 +4337,7 @@ class AllPlatformTests(BasePlatformTests):
         self.assertRegex(out, 'opt2 val2')
         self.assertRegex(out, 'opt3 val3')
         self.assertRegex(out, 'opt4 val4')
+        self.assertTrue(Path(self.builddir, '.gitignore').exists())
         self.build()
         self.run_tests()