Question

Another git question… I am in the following situation:

A1 ---- B1 ---- C1
                   \
                    > D ---- E ---- F
                   /
A2 ---- B2 ---- C2

Where {A1,B1,C1} and {A2,B2,C2} have no files in common (it’s the consequence of merging two different repositories, so I have currently two roots)

I would like the history to look like this

A1 ---- B1 ---- C1 ---- A2 ---- B2 ---- C2 ---- D ---- E --- F

But I cannot figure out how to do that with git-rebase, any idea?

Bonus: If I can keep the tags (which I have on all three branches) without having to do it manually…

Answer 1

I managed to do it with the following two commands, in sequence:

git filter-branch -f --parent-filter 'test $GIT_COMMIT = <a2> && echo "-p <c1>" || cat'
git filter-branch -f --parent-filter 'test $GIT_COMMIT = <new head> && echo "-p <c2>" || cat'

Of course, you have to replace <a2>, <c1>, <new head> etc. by the corresponding commit hashes. Note that the head’s hash changes after the first command, which is why I called it <new head> instead of just <d>.

It’s actually pretty straightforward: the first command sets C1 as A2’s parent. The second command fixes the graph by setting C2 as D’s only parent.