Fixed bug with oneofs in JSON decoding.
diff --git a/php/ext/google/protobuf/php-upb.c b/php/ext/google/protobuf/php-upb.c
index e7ec7d9..8a6ffb8 100644
--- a/php/ext/google/protobuf/php-upb.c
+++ b/php/ext/google/protobuf/php-upb.c
@@ -6794,7 +6794,7 @@
     return;
   }
 
-  if (upb_fielddef_containingoneof(f) &&
+  if (upb_fielddef_realcontainingoneof(f) &&
       upb_msg_whichoneof(msg, upb_fielddef_containingoneof(f))) {
     jsondec_err(d, "More than one field for this oneof.");
   }