git bisect for reachable commits only

Hi all,


I just found an interesting post how git bisect can trouble humans.
Full story is here
https://groups.google.com/forum/#!topic/git-users/v3__t42qbKE


My suggestion to fix it (ditto)


What I suggest change logic of bisecting to something like


      git config bisect.reachable true


This behaviour will reduce bisecting only to reachable commits between
bad/good points and will never goes away.

Maybe if commit will be found at merge commit git bisect can suggest
open another round trip to looking into not reachable way, but anyway
it should be explicit confirmed by user.


BTW, if bad commit is merge point with more than 2 parents, how git
bisect will find "first wrong commit" at the current state?


Thanks for the attention,


Oleg