Issue #16826: Don't check for PYTHONCASEOK when using -E.

This commit fixes a regression that sneaked into Python 3.3 where importlib
was not respecting -E when checking for the PYTHONCASEOK environment variable.

1 files changed, 4 insertions, 1 deletions

diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
index 91740571be..fad91cad92 100644
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -29,7 +29,10 @@ def _make_relax_case():
     if sys.platform.startswith(_CASE_INSENSITIVE_PLATFORMS):
         def _relax_case():
             """True if filenames must be checked case-insensitively."""
-            return b'PYTHONCASEOK' in _os.environ
+            if sys.flags.ignore_environment:
+                return False
+            else:
+                return b'PYTHONCASEOK' in _os.environ
     else:
         def _relax_case():
             """True if filenames must be checked case-insensitively."""