[solved] diverging git commit ids

[ffpp]

Hi,

after a long while of not maintaining it I am currently merging my patch into the current master sources from github.
I used to use the old repository url: http://git.openttd.org/openttd/trunk.git

But I realized that I get a redirect to the new repo:

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$ git remote show openttd
fatal: unable to update url base from redirection:
  asked for: http://git.openttd.org/openttd/trunk.git/info/refs?service=git-upload-pack
   redirect: https://github.com/OpenTTD/OpenTTD

I updated the remote and fetched the branch again, but during the merge I realized that I don't have a common merge-base anymore and this creates a million conflicts during the merge. The last merge against the old github url was done against this commit:

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d6df92b6d (openttd/master, openttd) (svn r27969) -Update from Eints: danish: 22 changes by Knogle

The last common commit is:

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$ git merge-base openttd nr/master
a580b4c21ee20179fa50bdab04aaeb586185fe8e
$ git --no-pager log -1 a580b4c21ee20179fa50bdab04aaeb586185fe8e
commit a580b4c21ee20179fa50bdab04aaeb586185fe8e
Author: bjarni <bjarni@openttd.org>
Date:   Mon Nov 29 20:03:04 2004 +0000

    (svn r855) BeOS: moved bemidi to os/beos/ (w-ber)

Then they diverge starting at the next commit:
old repo:

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$ git --no-pager log --oneline openttd | grep 'svn r856)'
4950c36769 (svn r856) Makefile: added the flags CYGWIN and MINGW to libdetection. They were missing in the autodetected makefile.config

new repo:

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$ git --no-pager log --oneline nr/master | grep 'svn r856)'
00d6b3609f (svn r856) Makefile: added the flags CYGWIN and MINGW to libdetection. They were missing in the autodetected makefile.config

Does anybody know what is the reason for this?

I think for my merge I will just cherry-pick all commits for my own patch onto a new branch or something.

[Eddi]

the way the new primary repo was created differs from the way the old copy repo was created. however, you should be able to use "rebase onto" to convert an old clone to the new repo

[ffpp]

I get several conflicts á la

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irst, rewinding head to replay your work on top of it...
Applying: (svn r5214) [languages] Re-done afrikaans change, this time proper
Using index info to reconstruct a base tree...
A	lang/unfinished/afrikaans.txt
Falling back to patching base and 3-way merge...
CONFLICT (modify/delete): lang/unfinished/afrikaans.txt deleted in HEAD and modified in (svn r5214) [languages] Re-done afrikaans change, this time proper. Version (svn r5214) [languages] Re-done afrikaans change, this time proper of lang/unfinished/afrikaans.txt left in tree.
error: Failed to merge in the changes.
Patch failed at 0001 (svn r5214) [languages] Re-done afrikaans change, this time proper
The copy of the patch that failed is found in: .git/rebase-apply/patch

Resolve all conflicts manually, mark them as resolved with
"git add/rm <conflicted_files>", then run "git rebase --continue".
You can instead skip this commit: run "git rebase --skip".
To abort and get back to the state before "git rebase", run "git rebase --abort".

[Eddi]

that sounds like you're trying to merge the entire old repo into the new one (or worse, the other way around), instead of just your changes?

in any case, unfinished/afrikaans.txt doesn't sound like a file containing vital information...

[JGR]

If doing a rebase you will need to explicitly exclude the old upstream.
Something like (with your branch checked out)

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git rebase --onto nr/master openttd/master

When I had this problem when merging the new upstream into my patchpack/repo, I used git replace to artificially join the two histories together at equivalent commits, which made things much easier.
That may be worth looking into if you get spurious conflicts or other issues trying to rebase or cherry-pick.

[ffpp]

that sounds like you're trying to merge the entire old repo into the new one (or worse, the other way around), instead of just your changes?

in any case, unfinished/afrikaans.txt doesn't sound like a file containing vital information...

I think that the old code base and the new one have diverged long before I made my first commit. So even when I try to rebase only my own changes onto the new master branch, it will use this old commit r5214 as oldest merge-base.
I tried to resolve those conflicts but they more complex than this one with the language text file.

If doing a rebase you will need to explicitly exclude the old upstream.
Something like (with your branch checked out)

Actually, the rebase worked now with JGR's suggestion. I was not aware of this rebase syntax where you can exclude a branch, the older master in this case.

Thanks for the help!