bpo-20392: Fix inconsistency with uppercase file extensions in mimetypes.guess_type (GH-30229)

1 files changed, 4 insertions, 6 deletions

diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 4750408..1aa3246 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -141,25 +141,23 @@ class MimeTypes:
                 type = 'text/plain'
             return type, None           # never compressed, so encoding is None
         base, ext = posixpath.splitext(url)
-        while ext in self.suffix_map:
-            base, ext = posixpath.splitext(base + self.suffix_map[ext])
+        while (ext_lower := ext.lower()) in self.suffix_map:
+            base, ext = posixpath.splitext(base + self.suffix_map[ext_lower])
+        # encodings_map is case sensitive
         if ext in self.encodings_map:
             encoding = self.encodings_map[ext]
             base, ext = posixpath.splitext(base)
         else:
             encoding = None
+        ext = ext.lower()
         types_map = self.types_map[True]
         if ext in types_map:
             return types_map[ext], encoding
-        elif ext.lower() in types_map:
-            return types_map[ext.lower()], encoding
         elif strict:
             return None, encoding
         types_map = self.types_map[False]
         if ext in types_map:
             return types_map[ext], encoding
-        elif ext.lower() in types_map:
-            return types_map[ext.lower()], encoding
         else:
             return None, encoding