type should not necessarily inherit when we read a file

panda/src/pnmimage/pnmImage.cxx

@@ -195,7 +195,6 @@ read(PNMReader *reader) {
   }
 
   copy_header_from(*reader);
-  _type = reader->get_type();
 
   // We reassign y_size after reading because we might have read a
   // truncated file.

panda/src/pnmimage/pnmImageHeader.cxx

@@ -38,7 +38,6 @@ read_header(const Filename &filename, PNMFileType *type) {
   PNMReader *reader = make_reader(filename, type);
   if (reader != (PNMReader *)NULL) {
     (*this) = (*reader);
-    _type = reader->get_type();
     delete reader;
     return true;
   }