There are already a lot of documentation about git bisect, already. Sadly, few explain HOW to do it properly when you’re not used to development.

Pre-requisite

You’ll need git and the git repository of OfflineIMAP, of course… ;-)

Clone the repository:

$ git clone https://github.com/OfflineIMAP/offlineimap.git

The commands

There are few simple commands to know.

  • Start a session
$ git bisect start
  • Mark as good
$ git bisect good
  • Mark as bad
$ git bisect bad
  • Ignore a step
$ git bisect skip
  • Stop a session
$ git bisect reset

Effective session

Before starting, you should know what version works and what version does not. This is required to start the process.

$ git bisect start
$ git bisect good v6.5.6
$ git bisect bad v6.5.7-rc2

From there, it’s you’re job to define if OfflineIMAP has the same issue or not.

$ ./offlineimap.py [THE USUAL OPTIONS]

Warning Be care to mark the checkouted version as good or bad ONLY if you’re sure about that.   A wrong declaration will put you in the wrong direction.

When in doubt, you must input the git bisect skip command.

Warning A failing run does NOT necessary mean you should declare it bad.   In such case, you must check what’s the error and if it’s the one you are bisecting. Otherwise, you must input git bisect skip command, too.

Understanding what is done

The process is fairly simple to understand. It just start in the middle of the patch series between the one marked as good and the one marked as bad. When a new good/bad is declared, it take the new middle between both and continue.

It’s a bit more complex if the git history is not linear but we don’t have to care about the internals.