LONDON—Hong Kong democracy activist Nathan Law called on voters in his home city to ignore a legislative election this month, the first under sweeping new rules imposed by Beijing, saying they should not lend the vote any legitimacy. The communist regime in Beijing announced in March broad changes to the former British colony’s electoral system, reducing the number of directly elected representatives and increasing the number of Beijing-approved officials in an expanded legislature. Candidates in the election, scheduled for Dec. 19 after being postponed for more than a year due to the coronavirus, are also vetted for their patriotism. “Just ignore them,” Law said in an interview from London at the Reuters Next conference. “We should not give any legitimacy to the election, we should not pretend we have an election—it is just a selection by Beijing.” A spokesman for the Chinese embassy did not immediately respond to a request for comment …