How to rebase commits from another repository with a different history?

Question

We have two Git repositories.

Repo 1. Commits: A, B, C. This repository was created from SVN history.

Repo 2. Commits: D, E, F. This repository was created without SVN history, just by using the working copy (as of commit C) which became the commit D. In another words, the file trees of the commits C und D are the same.

Now, we want to merge both repositories so we have the full history in one repository. Is there a way to "copy/rebase/something else" all the commits E..F onto C?

Answer 1

The easiest thing to do would be to add Repo 2 as a remote in Repo 1 using its physical path on disk and then simply cherry pick commits E and F on top of C.

So, in Repo 1 you would do:

git remote add repo2 C:\Path\To\Repo2
git fetch repo2

then, assuming E and F are the latest two commits in the master branch in Repo 2 and C is the latest commit in master in Repo 1, like this:

      master
     /
A-B-C
      repo2/master
     /
D-E-F

you would do:

git checkout master
git cherry-pick repo2/master~2..repo2/master

which will apply the patches from commits E and F on top of C:

           master
          /
A-B-C-E'-F'
      repo2/master
     /
D-E-F

Note that here I'm cherry-picking a range of commits, which is supported since Git 1.7.2.

Answer 2

Are these remote repositories? If both C and F are on the same local repository then you should be able to rebase the branch pointing to F onto the branch pointing to C. If not try this:

1. Locally in Repo1 run
   a. git remote add repo2 <Repo 2 URL>
   b. git push repo2 branchPointingToC
2. Then locally in Repo2 run
   a. git fetch
   b. git checkout branchPointingToF
   c. git rebase -i remotes/origin/branchPointingToC

(N.B. If instead you followed Enrico's answer but wanted to rebase you would use git rebase -i repo2/master in place of his git cherry-pick.)