Tuesday, December 1, 2009

Oh how I love git, let me count the ways!

Initially I kept separate repositories for each portion, most notably the EPI core and build system. Since Trac was selected for part of our web stack for getting stuff done, and it can be a tad pissy about multiple repositories, I've opted to create a "Merged" repository from the others. Essentially the Trac will require multiple Trac environments or a singular repository; while my we take the time to decide which to use, I just whip up a solution out of my hat like a good little geek &(^_^)&.

The trees were located in dixie:~/Projects/EPI/repo/ and still are. After backing up the repositories, I created a new 'work' tree to become the home of this merger, threw them together, and did some clean up. First I tried using git filter-branch and git format-patch together with a few other mungies to get the history retained how I wanted it, then I decided to screw it and just make branches reflect the history—even better then what I wanted.

I then used git format-patch to create patch sets, placing them in temporary directories. Rather then change the patch sets to reflect the merge (good task for perl scripting), I decided to rely on git mv for something more full proof then hacking patch files by hashed out automata.

Creating a new 'work' repository, I made an initial commit with a stub file, then created suitable branches for each in my original repos, which is a task easily automated in sh or Perl, for people with lots of branches. A little bit of git checkout and git am, then slurped up the patch sets bringing each repository (and it's associated branches) under one roof.

Creating the new merged 'master' was a simple octopus merge.

$ git checkout master
$ git merge repo1 repo2 ...
$ git mv ...
$ git commit -a

Job done, good night!

Note also, I wanted the trees merged, so conflicts were not even present, hehe.

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