alternate vcs: Fix _get_mod on windows

Author: cdevienne

src/towncrier/_vcs.py

@@ -17,6 +17,7 @@ def list_changed_files_compared_to_branch(
 
 
 def _get_mod(base_directory: str) -> VCSMod:
+    base_directory = os.path.abspath(base_directory)
     if os.path.exists(os.path.join(base_directory, ".git")):
         from . import _git
 
@@ -27,12 +28,14 @@ def _get_mod(base_directory: str) -> VCSMod:
         hg: VCSMod = _hg
 
         return hg
-    elif base_directory == "/":
-        from . import _novcs
-
-        return _novcs
     else:
-        return _get_mod(os.path.dirname(base_directory))
+        parent = os.path.dirname(base_directory)
+        if parent == base_directory:
+            from . import _novcs
+
+            return _novcs
+
+        return _get_mod(parent)
 
 
 def get_default_compare_branch(

src/towncrier/test/test_hg.py

@@ -1,6 +1,7 @@
 # Copyright (c) Amber Brown, 2015
 # See LICENSE for details.
 
+import os.path
 
 from pathlib import Path
 from subprocess import check_call
@@ -71,7 +72,7 @@ def test_hg(self):
             self.assertEqual(["main", "otherbranch"], branches)
 
             self.assertEqual(
-                ["changes/000.misc.rst"],
+                [os.path.join("changes", "000.misc.rst")],
                 _hg.list_changed_files_compared_to_branch(".", "main", False),
             )