When setting headers, fallback to `utf-8` if no encoding is specified yet. (#820)

* Headers: fallback to utf8 encoding

* Headers.__setitem__: use utf8 only if encoding is not set

diff --git a/httpx/_models.py b/httpx/_models.py
index 861e85fab6cd9b5604ad608b21e4b668784e408b..2bfa367ab911d4120364a2b733bf5c4885710951 100644 (file)
--- a/httpx/_models.py
+++ b/httpx/_models.py
@@ -515,8 +515,8 @@ class Headers(typing.MutableMapping[str, str]):
         Set the header `key` to `value`, removing any duplicate entries.
         Retains insertion order.
         """
-        set_key = key.lower().encode(self.encoding)
-        set_value = value.encode(self.encoding)
+        set_key = key.lower().encode(self._encoding or "utf-8")
+        set_value = value.encode(self._encoding or "utf-8")
 
         found_indexes = []
         for idx, (item_key, _) in enumerate(self._list):