[IPython-dev] Porting SVN history to Launchpad - help needed.

[Fernando Perez]

Hi all,

A couple of months ago we started the launchpad/bzr experiment, and
that has been very successful.  I don't think there's any doubt that
we'll stick with bzr for the time being, nobody feels like going back
to SVN.

To get things started,  Ville created a clean bzr branch without any
SVN history, partly because the scipy server at the time kept timing
out and the svn import into launchpad wasn't working.  Now that import
does function, and one can check out the bzr version of SVN trunk via

bzr branch lp:~vcs-imports/ipython/main/ ipython-svn

The main ipython dev branch (our new 'trunk') can be obtained with

bzr branch lp:ipython

The problem I'm having is how to merge the latter into the former
while preserving the full  history.  Because the bzr trunk was
initialized without any SVN history, every attempt I've made so far
has failed.  I've tried bzr merge and rebase with various flags,
without any success.  I'm not even sure it's possible to do this
cleanly, I'm afraid.

The SVN trunk has several years of history that I'm not willing to
lose (I already made the mistake of losing all  project history in the
CVS->SVN transition, I won't repeat that).  I'd love to hear from
anyone who might know how to make this merge, if it is possible.  If
it can't be made with bzr merge tools, I guess we can try to produce a
set of bundles and apply them one by one or as a lump change with one
gigantic commit message that preserves the other log...

We're probably going to lose history no matter what, because of the
'branch folding' problem I mentioned earlier.  The current bzr 'trunk'
has a really funky log that shows these, and hopefully we won't make
these mistakes with bzr in the future.  But I'd like to minimize the
losses, so I'd love if a bzr guru amongst us knows the magic trick.

Cheers,

f