Python is now hosted in a Mercurial repository. This page is currently outdated.

Checking out the Python Source Code with Git

Note that the Python source is eventually going to be moved from Subversion of Mercurial. When that happens, the Git repositories will likely stop being updated.

Also note that these instructions should not be considered a good introduction to typical Git usage. They are necessarily complex because they try to be efficient in network bandwidth while still working with the existing Subversion infrastructure.


Python's source code currently maintained under the Subversion revision control system. This document describes how to checkout the source as a Git repository. Some advantages of using git are:

* The entire history is available locally so you easily work without network access.

* Git has some nice tools for dealing with local branches (rebasing them, for example).

* Operations like git diff and git log are much faster than the Subversion equivalents.

Doing the initial checkout

Git's pack format is efficient but the entire VC history of Python still consumes a lot of space (currently around 90 MB). You could use git-svn to create a local repository (please don't do that) but it's much faster to use the native git protocol. To allow that, there are Git repositories on that are updated every hour. Changes since that time can be pulled using git-svn.

Ensure that you have a recent Git (at least version 1.5.1). The following commands will initialize an empty repository::

    mkdir trunk.git
    cd trunk.git
    git init

Tell git-svn where the Subversion repository is located (so you can use git-svn to push and pull changes to the SVN server). If you have read-write access use::

    git svn init svn+ssh://

Tell Git where the data can be fetched using the Git protocol. This is more efficient than using the Subversion protocol, especially if you are far behind the head::

    git remote add git-svn git://
    git config remote.git-svn.fetch refs/heads/master:refs/remotes/git-svn

The following command populates the local repository (this will download approximately 90 MB of data from Note that you can use the git clone command to efficiently make local copies of the repository. To fetch that data into the local git-svn branch::

    git fetch git-svn

We don't do our development on the git-svn branch since that follows the head of the public Subversion repository. Our main development branch is called 'master', athough we can create as many others as we like. Merge the changes from the git-svn branch into our development branch (normally you would first rebase your changes in master on top of git-svn but right now we don't have any)::

     git pull git-svn master

The local branch master and the remote branch git-svn now contain identical trees. Use git-svn to get up to the minute changes from the SVN server::

    git svn fetch

This should complete quickly because nearly all the data is already local and the git-svn command will merely go through the logs and extract the Subversion revision numbers.

Keeping up-to-date

Using the git svn fetch command closely matches the behavior of the svn update command. It will fetch new versions from the Subversion repository and then rebase your local changes on top of them::

    git svn fetch

Note that this can be slow if your repository is far behind the Subversion repository. The most efficient method to update your local respository is to use the Git protocol before using git svn. To fetch new commits, run::

    git fetch git-svn

If you have no local changes, you can do a fast-forward merge of upstream commits into your current development branch::

    git merge git-svn

However, if you have local changes then you probably want to use rebase as it more closely matches the behavior of svn up. This will essentially extract your changes as a series of patches and reapply them to the git-svn (i.e. most recent) version of the tree::

    git rebase git-svn

Sharing work

Please refer to the Git SVN tutorial for general instructions on how to interact with a Subversion repository. The git format-patch, git am and git apply commands are very useful when dealing with patches.

If you have write access to the SVN repository then you can use git svn dcommit to push your local commits directly into the public SVN repository. Take extra care before using dcommit. It's a good idea to use git log or gitk to check what will be sent before actually running dcommit. Also note that your local copy must be up-to-date (e.g. via git svn rebase) for dcommit to work.

Python 3 branch

There is also a Git repository for the py3k branch. The following commands assume read-write access to the SVN repository and will create a local repository (the important difference is with the SVN and Git URLs)::

    mkdir py3k.git
    cd py3k.git
    git init
    git svn init svn+ssh://
    git remote add git-svn git://
    git config remote.git-svn.fetch refs/heads/master:refs/remotes/git-svn
    git fetch git-svn
    git pull git-svn master

Git (last edited 2012-01-09 15:58:47 by √ČricAraujo)

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