ALTER TABLE ADD INDEX - PROCESSLIST - PROGRESS NOT RIGHT (extend progress report for partitioning)

Hi guys, i was running some ALTER TABLE xxx ADD KEY yyy (zzz)
and watching status from
SELECT time_ms/1000,state,info,stage,max_stage,progress FROM information_schema.processlist WHERE info!=''

and i get 4 status:
1)COPYING TO TMP TABLE
2)REPAIR BY SORTING
3)CREATING INDEX
4)REPAIR BY SORTING

to problema is stage/progress
the max_stage was = 2 while running 1,2
when it started 3,4 the stage,max_stage and progress was set to 0
in other words, the max_stage was 'calculated' wrong at stage 1 and 2, it should be 4 instead of 2
in stage 3,4 the stage, max_stage and progress couldn't help showing the progress of operation (i can't know how many time or progress i will wait)

my table have about 1,5GB of data, in a small table i couldn't see this since it's really fast

thankx