templater: fix if() to not evaluate False as bool('False') Before, False was True. This patch fixes the issue by processing True/False transparently. The other values (including integer 0) are tested as strings for backward compatibility, which means "if(latesttagdistance)" never be False. Should we change the behavior of "if(0)" as well?

templater: make it clearer that _flatten() omits None

revset: support "follow(renamed.py, e22f4f3f06c3)" (issue5334) v2: fixes from review