return empty list when nothing's found (#2586)
return empty list when nothing's found (#2586)

[fix] imdb_watchlist no longer crashes with empty lists
malkavi/Flexget,ianstalk/Flexget,crawln45/Flexget,malkavi/Flexget,ianstalk/Flexget,malkavi/Flexget,malkavi/Flexget,Flexget/Flexget,crawln45/Flexget,crawln45/Flexget,Flexget/Flexget,crawln45/Flexget,Flexget/Flexget,Flexget/Flexget,ianstalk/Flexget