[Mod]change logic of is_convert_required function
[Mod]change logic of is_convert_required function

andrewchenshx/vnpy,andrewchenshx/vnpy,bigdig/vnpy,msincenselee/vnpy,bigdig/vnpy,vnpy/vnpy,msincenselee/vnpy,andrewchenshx/vnpy,msincenselee/vnpy,andrewchenshx/vnpy,bigdig/vnpy,bigdig/vnpy,andrewchenshx/vnpy,msincenselee/vnpy,vnpy/vnpy