Choosing a moment for the Bazaar switchover.

Jason Earl jearl at
Tue Mar 31 20:36:28 BST 2009

I will say that Guido seems to have stolen a bit of my thunder.  I
decided to sit on this email overnight (to give myself a little more
time to think about what I should say), and I woke up this morning to
see most of my thoughts spilled all over a different thread.

Karl Fogel <karl.fogel at> writes:

> Jason Earl <jearl at> writes:
>> That being the case, I don't think that it would be wise to switch to
>> bzr right now.  For one thing a minor bug in bzr's fast-import plugin
>> has made it impossible for me to generate new emacs-merges
>> repositories from Andreas' git repository in anything but the
>> bleeding edge brisbane-core formats.  I tried poking at this bug a
>> bit myself, but I quickly found myself out of my depth.  Ian
>> Clatworthy is working on it now.  Here's the bug report if you are
>> interested.
> *nod*  Thank you; yes, that's very helpful to know.
>> The other advantage of waiting is that bzr really is still in a state
>> of considerable flux.  I have really come to love bzr, but it is hard
>> to ignore the fact that the bzr devs make considerable changes on a
>> monthly basis.  I think that it might well be in Emacs' best
>> interests to at least wait until the new repository format lands.
> I'd love to know what causes your impression of "a state of flux".  I
> have some ideas, but don't want to taint your impressions by stating
> them yet -- would rather hear from you.

That's an excellent question.  I hope I can give a satisfactory answer.
I would like to note that I personally don't consider bzr's rate of
change to be a bad thing.  To a large extent bzr has made considerable
changes because it is responding positively to end user input.  When I
first started playing with bzr I didn't really consider it to be a
contender in the distributed VCS game.  I'd played around with Gnu Arch
(and baz), Monotone, Git, and Mercurial, and I preferred both git and
Mercurial to Bazaar.  I started using bzr more seriously because it
became a FSF project and I thought I could help the Emacs community out
by providing a bzr repo, not because I was particularly interested in
bzr.  Since then the bzr development community has changed my mind
completely.  The issues that were raised have, for the most part, been
handled, and I have come to appreciate both bzr's great user interface
and its matchless flexibility.

That being the case.  In the time that I have been running I have installed 13 different stable versions of
bzr (not including a few point releases).  It is hard to argue that bzr
isn't in a state of flux when a new stable version is available once a

The big thing, however, has got to be the repo and branch format issues.
Anyone that's been paying attention to this list at all knows that the
bzr team has been working on the new brisbane-core format for some time,
and that to a large extent it has been designed around the issues that
have come up with large repositories like the Emacs repository.  I think
that a large project would be very foolish to switch to bzr before that
format landed.  Conversions are difficult and time consuming projects
and the trick is to only do them once.  The last thing that I would want
for the Emacs development community is to create a new repo in 0.92 pack
format and 6 months later have a version of bzr comes out that warns you
to upgrade remote branches.

The current default format of bzr is being phased out.  Saying that bzr
is in a "state of flux" is probably kind.  Heck, I can't even do a
conversion from git right now into the pack 0.92 format because
fast-import is broken for that format.  I can, however, create a
brisbane core repository.

> NOTE: I think the Bazaar developers would like to know, too, so I've
> set Reply-to on this mail to go to the Bazaar list.  The thread would
> get off-topic for emacs-devel at this point anyway -- anyone who does
> a follow-up-to-all, please take emacs-devel@ off the recipient list.

Hopefully the bzr development team really did want to know about this.
If not please excuse me.  I am a huge fan of bzr, and I really think
that the project is on the right track.


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