Explicit test a blank response instead of any non-json response

Author: michelts

convertapi/client.py

@@ -51,11 +51,11 @@ def handle_response(self, r):
 			except ValueError:
 				raise e
 
-		try:
-			return r.json()
-		except simplejson.errors.JSONDecodeError as e:
+		if r.content == b'':
 			raise AsyncConversionInProgress
 
+		return r.json()
+
 	def url(self, path):
 		return "%s%s?Secret=%s" % (convertapi.base_uri, path, convertapi.api_secret)