Accept environment variables with different cases on Windows. Fixes #607

src/debugpy/launcher/handlers.py

@@ -79,16 +79,6 @@ def property_or_debug_option(prop_name, flag_name):
 
  env = os.environ.copy()
  env_changes = request("env", json.object((unicode, type(None))))
- if sys.platform == "win32":
- # Environment variables are case-insensitive on Win32, so we need to normalize
- # both dicts to make sure that env vars specified in the debug configuration
- # overwrite the global env vars correctly. If debug config has entries that
- # differ in case only, that's an error.
- env = {k.upper(): v for k, v in os.environ.items()}
- n = len(env_changes)
- env_changes = {k.upper(): v for k, v in env_changes.items()}
- if len(env_changes) != n:
- raise request.isnt_valid('Duplicate entries in "env"')
  if "DEBUGPY_TEST" in env:
  # If we're running as part of a debugpy test, make sure that codecov is not
  # applied to the debuggee, since it will conflict with pydevd.

tests/debugpy/test_env.py

@@ -48,13 +48,14 @@ def code_to_debug():
  else:
  assert env[varname] == "42"
  elif sys.platform == "win32":
- # On Win32, variable names are case-insensitive, so debug config should
- # replace the global env var even if there is a case mismatch.
+ # On Win32, although variable names are case-insensitive for matching, they're still
+ # case-preserving (and it's even possible to have something as Path and PATH even
+ # though later on one would override the other).
+ assert varname.lower() not in env
  if new_value is None:
- assert varname not in env
+ assert env[varname] == "1"
  else:
  assert env[varname] == "42"
- assert varname.lower() not in env
  else:
  # On other platforms, variable names are case-sensitive, so case mismatch
  # should result in two different variables.