incorporate review feedback from @EliahKagan

git/util.py

@@ -490,7 +490,8 @@ def is_cygwin_git(git_executable: PathLike) -> bool: ...
 
 
 def is_cygwin_git(git_executable: Union[None, PathLike]) -> bool:
-    _logger.debug(f"sys.platform = {sys.platform}, git_executable = {git_executable}")
+    # TODO: when py3.7 support is dropped, use the new interpolation f"{variable=}"
+    _logger.debug(f"sys.platform={sys.platform!r}, git_executable={git_executable!r}")
     if sys.platform != "cygwin":
         return False
     elif git_executable is None:

test/test_util.py

@@ -354,6 +354,7 @@ class TestIsCygwinGit:
     """Tests for :func:`is_cygwin_git`"""
 
     def test_on_path_executable(self):
+        # Currently we assume tests run on Cygwin use Cygwin git. See #533 and #1455 for background.
         if sys.platform == "cygwin":
             assert is_cygwin_git("git")
         else: