Mix and match version control

By: on January 21, 2009

LShift’s standard version control platform these days is Mercurial, but just before we adopted it, I started a project using Trac and Subversion, mostly because that’s what Trac does out of the box.

Later, we branched the project to add a large new project, and during that branch we converted from using ant to Maven and modularised the project, resulting in a lot of moved files. This made what we were doing on the branch a lot easier, but left us with a merge that subversion wasn’t capable of, even though we had used svn mv to move all the files.

What was capable of the merge was Mercurial. I imported the whole subversion repository using hg convert. See the convert extension documentation. It works exactly as described, but make sure you have 1.0.1 or later – I had problems with earlier versions.

The merge went reasonably well, so I was left with a merged version in a Mercurial repository. I was going to switch to using Mercurial, and its Trac integration, when I discovered that couldn’t cope with multiple repositories. The Trac instance was managing several different source projects, which would have to go into several mercurial repositories, which I couldn’t merge together in any satisfactory way.

There are several projects around to address this (I’ll probably cover them in another post), none of which are ready for production yet. I decided the most expedient thing would be to try and generate a patch for my merge, and apply it to the subversion repository.

A conventional patch would lose the version history of all the moved files, so I decided a git diff would do the job. You can certainly, with some patience, get git-svn to do this, and understand what it was doing. Lacking that patience, I wrote a script to do the job. It parses the git diff and deals with any directory creation needed, calls to svn mv, svn add, and svn rm as required by the diff. It actually turns out to be a bit more work than I was expecting, so I’ve published it here.



  1. Tom Berger says:

    Bazaar actually has a plugin which lets you work with subversion and move stuff between bzr branches and svn back and forth without losing history.

  2. Mark says:

    Using multiple version control tools within large teams is becoming very common. One I prefer to automate our process is Accurev because it increases our ability to work in more ways possible and makes things visually obvious to the end users regardless of where they reside. I have no patience or resources when it comes to version control so went commercial. I wonder how Mg compares with Git for understanding where in the process a developer fits and being able to control what is seen, promoted and built?

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