When using easypost, it could exist more than one tracking
link. In this case they are stored as a json and the method
open_url try to load it as a list of url. Then it checks if there is
more than one url or not. However in a single case, there is only one
string and the lenght of a string is the number of chracter inside that
is often more than one.
Arnold Moyaux
86cb5203a1