TIP: using git-bisect (Was: nnimap no workee once again)

[Steinar Bang <sb@dod.no>]

>>>>> Harry Putnam <reader@newsguy.com>:
> Steinar Bang <sb@dod.no> writes:
>> Have you tried using git bisect to narrow it down to a specific commit?

> I've never bisected a git... I Disected a few frogs once : )

Googling for git-bisect should give you the docs
 http://book.git-scm.com/5_finding_issues_-_git_bisect.html

> Honestly I have no idea what you are talking about... but it did get
> me thinking to update gnus and see if the problem persists.

Ok.  Sounds like the not working didn't come because of a "git pull"...?
If so, it's a good idea to say so.  It narrows down the possibilities.

Using git bisect applies when a "git pull" leaves you with a broken
gnus.  What I do in that case, is:
 1. Find the SHA1 from before the last pull (the contents of
    .git/ORIG_HEAD), this will be "good"
 2. Start the command
     git bisect start bad good
    where bad is a sha1 hash, or tag, that you know is bad, eg. HEAD and
    good is a sha1 hash, or tag, that you know is good.  If I've done
    nothing except pulling from upstream in my repo, and the previous
    version was ok, I can actually do this
     git bisect start HEAD ORIG_HEAD
    then you loop, doing this:
     a. do "make clean" followed by "make" (or "./configure && make" if
        that's your preference)
     b. start a new emacs and start gnus and see if the problem persist.
        If the problem persists, do
         git bisect bad
        If the problem isn't there, do
         git bisect good
        If "git bisect" tells me that it has found the first offending
        commit, then go to 3, else go to a.
 3. Copy the text from "git bisect" where it found the offending commit,
    and send it to the gnus group
 4. Use "git bisect reset" to set the working directory back to normal,
    then decide if I want to try to fix the issue yourself, or pull
    back to the last good version, until it can be fixed, and then "make
    clean" and "make" gnus