percent_complete is required so set 0 as default

issue3470
review1541002
(transplanted from b111827178f3cb41354b782b6aa62090ffb745f0)

--HG--
extra : transplant_source : %B1%11%82qx%F3%CBA5Kx%2Bj%A6%20%90%FF%B7E%F0