tests/test-progress.out

localrepo: refactor prepush logic

Simplifies the prepush check logic and makes it a lot more direct and
comprehensible. Instead of comparing the total local vs. remote head count, it
compares the number of new vs. removed heads.

% test default params, display nothing because of delay
% test with delay=0, refresh=0

loop [                                                                    ] 0/3
loop [=====================>                                              ] 1/3
loop [============================================>                       ] 2/3
                                                                                
% test refresh is taken in account
% test format options 1

0/2 loop lo
1/2 loop lo
                                                                                
% test format options 2

0/2 p.0 [                                                                     ]
1/2 p.1 [=================================>                                   ]
                                                                                
% test format options and indeterminate progress

0 loop.0               [ <=>                                                  ]
1 loop.1               [  <=>                                                 ]
                                                                                
% test immediate progress completion