Short-bow Bug
Wow just tested this in the mists and its happening for every weapon, I even tested it on engi. It also happens if you have no endurance but try and dodge roll.
Edit: Apparently its getting fixed in balance patch in 2 weeks:
https://forum-en.gw2archive.eu/forum/support/bugs/Auto-attack-cancelled-on-dodge-merged/page/2
(edited by Nugget.8031)