Fix type checking breakage (#865)

diff --git a/httpx/_content_streams.py b/httpx/_content_streams.py
index 1d351677762ef490dd663fb39f88f08ed111839f..5f3237e1bbad8313f8d29266041be964d846d707 100644 (file)
--- a/httpx/_content_streams.py
+++ b/httpx/_content_streams.py
@@ -263,6 +263,7 @@ class MultipartStream(ContentStream):
             return b"".join(parts)
 
         def render_data(self) -> bytes:
+            content: typing.Union[str, bytes]
             if isinstance(self.file, str):
                 content = self.file
             else: