Fixed.
It's not about nitro boots, it's about http://www.db.pandawow.me?spell=108212/burst-of-speed
If you use http://www.db.pandawow.me?spell=108212/burst-of-speed, and then remove buff (with right click or macros) before its full duration, you will still have 170% speed.
I tested and seems this is the old bug, it exists even without this fix.
upd:
http://www.db.pandawow.me?spell=108212/burst-of-speed is fixed