Fix broken umlauts in filenames (ansible#1339)

examples/playbooks/with-umlaut-ä.yml

@@ -0,0 +1,5 @@
+---
+- hosts:
+  - localhost
+  roles:
+  - name: node

src/ansiblelint/file_utils.py

@@ -166,15 +166,15 @@ def __repr__(self) -> str:
 def get_yaml_files(options: Namespace) -> Dict[str, Any]:
     """Find all yaml files."""
     # git is preferred as it also considers .gitignore
-    git_command = ['git', 'ls-files', '*.yaml', '*.yml']
+    git_command = ['git', 'ls-files', '-z', '*.yaml', '*.yml']
     _logger.info("Discovering files to lint: %s", ' '.join(git_command))
 
     out = None
 
     try:
         out = subprocess.check_output(
             git_command, stderr=subprocess.STDOUT, universal_newlines=True
-        ).splitlines()
+        ).split("\x00")
     except subprocess.CalledProcessError as exc:
         _logger.warning(
             "Failed to discover yaml files to lint using git: %s",

test/TestUtils.py

@@ -267,6 +267,18 @@ def test_get_yaml_files_silent(is_in_git, monkeypatch, capsys):
     )
 
 
+def test_get_yaml_files_umlaut(monkeypatch, capsys):
+    """Verify that filenames containing German umlauts are not garbled by the get_yaml_files."""
+    options = cli.get_config([])
+    test_dir = Path(__file__).resolve().parent
+    lint_path = test_dir / '..' / 'examples' / 'playbooks'
+
+    monkeypatch.chdir(str(lint_path))
+    files = file_utils.get_yaml_files(options)
+    assert '"with-umlaut-\\303\\244.yml"' not in files
+    assert 'with-umlaut-ä.yml' in files
+
+
 def test_logger_debug(caplog):
     """Test that the double verbosity arg causes logger to be DEBUG."""
     options = cli.get_config(['-vv'])