LONDON (Reuters) - British online grocer Ocado will open its first "mini" robotic warehouse in Bristol, western England, by early 2021, it said on Thursday, signalling its warehouse technology can be rolled out more quickly and in a bigger range of locations.While Ocado's retail business holds only a 1.4% share of Britain's grocery market, its technology has powered the group's 8.1 billion pound ($10.4 billion) stock market valuation, enabling it to secure partnership deals with supermarket..