Ignore Content-Encoding headers that are invalid (#196)

httpx/models.py

@@ -780,8 +780,11 @@ class BaseResponse:
             values = self.headers.getlist("content-encoding", split_commas=True)
             for value in values:
                 value = value.strip().lower()
-                decoder_cls = SUPPORTED_DECODERS[value]
-                decoders.append(decoder_cls())
+                try:
+                    decoder_cls = SUPPORTED_DECODERS[value]
+                    decoders.append(decoder_cls())
+                except KeyError:
+                    continue
 
             if len(decoders) == 1:
                 self._decoder = decoders[0]

tests/test_decoders.py

@@ -86,3 +86,12 @@ def test_decoding_errors(header_value):
     with pytest.raises(httpx.exceptions.DecodingError):
         response = httpx.Response(200, headers=headers, content=compressed_body)
         response.content
+
+
+def test_invalid_content_encoding_header(header_value):
+    headers = [(b"Content-Encoding", header_value)]
+    body = b"test 123"
+
+    response = httpx.Response(200, headers=headers, content=body)
+
+    assert response.read() == body