Use legacy compatible converter

Older versions of Seaside don't have a dedicated ASCII converter.
Use UTF-8 instead.

repository/Seaside-Core.package/WAComboResponse.class/instance/commit.st

@@ -15,8 +15,10 @@ commit
 	could be written to the external stream directly (in particular, writing of
 	singel characters doesn't work). Luckily, the encoders already translate
 	characters to bytes, so we only need to wrap the stream with the appropariate
-	encoder. Header data is always ASCII encoded."
-	encodingStream := (GRCodec forEncoding: 'ascii') encoderFor: externalStream.
+	encoder. Header data is always ASCII encoded.
+	Because older versions of Seaside don't have a dedicated ASCII encoder we
+	use UTF-8 here (ASCII is a subset of UTF-8)."
+	encodingStream := (GRCodec forEncoding: 'utf-8') encoderFor: externalStream.
 	self
 		writeStatusOn: encodingStream;
 		writeHeadersOn: encodingStream;