Use comma rather than semicolon to split header values (#698)

src/PostgREST/ApiRequest.hs

@@ -176,7 +176,7 @@ userApiRequest schema req reqBody =
   hasPrefer val   = any (\(h,v) -> h == "Prefer" && val `elem` split v) hdrs
     where
         split :: BS.ByteString -> [Text]
-        split = map T.strip . T.split (==';') . toS
+        split = map T.strip . T.split (==',') . toS
   singular        = hasPrefer "plurality=singular"
   representation
     | hasPrefer "return=representation" = Full

src/PostgREST/OpenAPI.hs

@@ -164,7 +164,7 @@ makeGetParams cs =
 
 makePostParams :: Text -> [Param]
 makePostParams tn =
-  [ makePreferParam ["return=representation", "return=representation;plurality=singular",
+  [ makePreferParam ["return=representation", "return=representation,plurality=singular",
                      "return=minimal", "return=none"]
   , (mempty :: Param)
     & name        .~ "body"