For streaming signature do not save content-encoding in PutObject() (#3776)

Content-Encoding is set to "aws-chunked" which is an S3 specific
API value which is no meaning for an object. This is how S3
behaves as well for a streaming signature uploaded object.

cmd/object-handlers.go

@@ -421,6 +421,13 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
 
 	// Extract metadata to be saved from incoming HTTP header.
 	metadata := extractMetadataFromHeader(r.Header)
+	if rAuthType == authTypeStreamingSigned {
+		// Make sure to delete the content-encoding parameter
+		// for a streaming signature which is set to value
+		// "aws-chunked"
+		delete(metadata, "content-encoding")
+	}
+
 	// Make sure we hex encode md5sum here.
 	metadata["md5Sum"] = hex.EncodeToString(md5Bytes)