Pushing to Repositories With Different Content

Same branch name but different content?#

You might be asking yourself at this point: what happens if both repositories have a branch with the same name but different content?

Let’s see! Type this out.

1   mkdir git_origin
2   cd git_origin
3   git init
4   echo 'first commit' > file1
5   git add file1
6   git commit -am file1
7   cd ..
8   git clone git_origin git_clone
9   cd git_clone
10  git checkout -b abranch
11  echo 'cloned abranch commit' >> file1
12  git commit -am 'cloned abranch commit'
13  cd ../git_origin
14  git checkout -b abranch
15  echo 'origin abranch commit' >> file1
16  git commit -am 'origin abranch commit'
17  cd ../git_clone
18  git push origin abranch:abranch

Expected output#

The output of the last command will look something like this:

To /lgthw_pushing/git_origin
 ! [rejected]        abranch -> abranch (fetch first)
error: failed to push some refs to '/lgthw_pushing/git_origin'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

Read the output carefully. It tells you exactly what’s going on.

Breaking it down#

Updates were rejected because the remote contains work that you do not have locally.

The remote (the origin) has a commit (with the content: origin abranch commit) that you have no record of locally in your branch with the same name.

It goes on:

This is usually caused by another repository pushing to the same ref.

It has correctly diagnosed the problem as another repository (git_remote), pushing to the same branch name (ref) on the receiving remote. Finally, it offers some advice.

You may want to first integrate the remote changes (e.g., 'git pull ...') before pushing again.

Performing a fetch and merge#

But by now, you should know better than to git pull without thinking! Do a fetch and merge to really understand what is going on:

19  git fetch origin

Check the branches you have locally:

20  git branch -v -a

Observe that the remotes/origin/abranch branch you now have locally is different from the local abranch branch.

To complete your manual pull, merge the remote branch into the local:

21  git merge remotes/origin/abranch

Follow the instructions to resolve the conflict and commit the result.

Later, we will cover doing a rebase here rather than a merge for a cleaner history!

Note: You may be wondering why you don’t push at this point. A push, in this specific case, will not work because you are pushing a conflicting change to a repository that is not a bare Git repository. This is explained further in a later section on bare Git repositories. If you clone from a Git server, then you will be able to push back in this case as normal, as those servers have bare repositories.