Fix pip config parsing for multiple extra-index-urls

metaflow/plugins/pypi/pip.py

@@ -324,7 +324,9 @@ def indices(self, prefix):
                 key, value = line.split("=", 1)
                 _, key = key.split(".")
                 if key in ("index-url", "extra-index-url"):
-                    values = map(lambda x: x.strip("'\""), re.split("\s+", value, re.M))
+                    values = map(
+                        lambda x: x.strip("'\""), re.split(r"\\n|\s+", value, re.M)
+                    )
                     (indices if key == "index-url" else extra_indices).extend(values)
         except Exception:
             pass

test/plugins/pip/test_pip_indices.py

@@ -0,0 +1,32 @@
+from unittest.mock import MagicMock
+
+from metaflow.plugins.pypi.pip import Pip
+
+
+def _make_pip():
+    """Create a bare Pip instance for testing."""
+    pip = object.__new__(Pip)
+    return pip
+
+
+def test_multiple_extra_index_urls_literal_newline(monkeypatch):
+    """Regression test: pip config list separates multiple URLs with literal \\n."""
+    pip = _make_pip()
+    config_output = (
+        "global.index-url='https://pypi.org/simple'\n"
+        r"global.extra-index-url='https://extra1.example.com/simple'\n'https://extra2.example.com/simple'"
+    )
+
+    # Use monkeypatch instead of unittest.mock.patch
+    mock_call = MagicMock(return_value=config_output)
+    monkeypatch.setattr(pip, "_call", mock_call)
+
+    # Execute
+    index, extras = pip.indices("dummy")
+
+    # Assert
+    assert index == "https://pypi.org/simple"
+    assert extras == [
+        "https://extra1.example.com/simple",
+        "https://extra2.example.com/simple",
+    ]