Moving depmixS4 development to GitHub

We have migrated development of depmixS4 from RForge to GitHUb! While in the end this turned out to be relatively straightforward, it took a little puzzling and a lot of internet searching. We ideally wanted to keep the commit history and releases/tags to remain intact on GitHub. Moreover, we wanted to migrate parts of the svn repository to separate git repositories. For instance, the RForge svn repository contained subfolders for depmixS4 as well as the legacy R package depmix, and these need separate repositories on GitHub. For example, relevant subfolders in the RForge repository were:

papers/
    jss/
pkg/
    depmix/
    depmixS4/
tags/
    depmix-0.9.8/
    ...
    release-1.3.2/

I first tried to use svn2git, but didn’t succeed in connecting to the RForge repository via ssh. So I went with git-svn. I looked at various websites, but in the end I think I mainly followed advice from here and here. I created an svnauthors.txt file to transfer commits from the svn over to GitHub. The contents of this file were roughly

usename1 = FirstName1 LastName1 <email@users.noreply.github.com>
username2 = FirstName2 LastName2 <email@users.noreply.github.com>

where of course you would need to replace these with real names and email addresses. Then, to migrate the depmixS4 part to GitHub, in the terminal, I used

mkdir svn-to-github
cd svn-to-github
git svn clone svn+ssh://username@svn.r-forge.r-project.org/svnroot/depmix/ --trunk pkg/depmixS4 --tags tags/release*  --authors-file svnauthors.txt

Note that I put the required subfolder as the trunk argument, and used the tags argument to include only tags starting with release (in order to filter out the tags for depmix). This took some time and multiple password entries, but it seemingly worked! In the svn-to-github folder, there was now a folder called depmix folder (note that the name is taken from the svn address, not the trunk argument) with an initialized git repository. Some further work is needed to transfer the svn tags to git tags, so I did the following:

mv depmix depmixS4 // rename folder
cd depmixS4
git branch -a // check for branches
// turn branches into tags
for tag in `git branch -r | grep "tags/" | sed 's/ tags\///'`; do
  git tag -a -m"Converting SVN tags" $tag refs/remotes/$tag
done
git tag // show the tags

I did some further tests to see whether the repository was working as intended (again following this advice), which seemed to be the case. Then I created an empty repository on GitHub called depmixS4, ready to receive the local git repository:

git remote add origin https://github.com/depmix/depmixS4.git
git push --all
git push --tags // tags are not included in all

And voila, a working git repository or GitHub with the commit history and tags from RForge. Fantastic!