Push to master commit made on a detached head

Question

I wanted to redo changes from a previous commit.

Maxims-MacBook-Air:hellodebug.com maximveksler$ git log
commit 7f9dd753d39fd65b4272af713ef9c07a9f84f016
Author: Maxim Veksler <maxim@vekslers.org>
Date:   Sun Dec 28 09:12:17 2014 +0200

    Imagine a Supercomputer Helping You Fix Bugs Faster

commit 54561ed320633e72bb35a7ab668a9996e6ffca8f
Author: Maxim Veksler <maxim@vekslers.org>
Date:   Sun Dec 28 08:57:25 2014 +0200

    highcharts tweaks

commit d57144cbd004b3b9e893e8d50d7077634824ce9a
Author: Genady Okrain <genady@okrain.com>
Date:   Mon Dec 22 18:46:21 2014 +0200

    sash api

So I've broke it on 7f9dd753d39fd65b4272af713ef9c07a9f84f016 and decided to unbreak it from 54561ed320633e72bb35a7ab668a9996e6ffca8f

Maxims-MacBook-Air:hellodebug.com maximveksler$ git checkout 54561ed320633e72bb35a7ab668a9996e6ffca8f
Note: checking out '54561ed320633e72bb35a7ab668a9996e6ffca8f'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b new_branch_name

HEAD is now at 54561ed... highcharts tweaks

So far so good, now let's do the fixing.

Maxims-MacBook-Air:hellodebug.com maximveksler$ git commit -a -m'Back to not fucking it up'
[detached HEAD b5cb3e4] Back to not fucking it up

But now I need to push this back into master, and upsteam. Here comes the messy part...

Maxims-MacBook-Air:hellodebug.com maximveksler$ git checkout HEAD
Maxims-MacBook-Air:hellodebug.com maximveksler$ git status
HEAD detached from 54561ed
nothing to commit, working directory clean
Maxims-MacBook-Air:hellodebug.com maximveksler$ git push
fatal: You are not currently on a branch.
To push the history leading to the current (detached HEAD)
state now, use

    git push origin HEAD:<name-of-remote-branch>

Maxims-MacBook-Air:hellodebug.com maximveksler$ git push origin HEAD:master
Warning: Permanently added 'github.com,192.30.252.131' (RSA) to the list of known hosts.
To git@github.com:maximveksler/hellodebug.com.git
 ! [rejected]        HEAD -> master (non-fast-forward)
error: failed to push some refs to 'git@github.com:maximveksler/hellodebug.com.git'
hint: Updates were rejected because a pushed branch tip is behind its remote
hint: counterpart. Check out this branch and 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.

Right... so now I'm stuck. Let's try some more wonky stuff

Maxims-MacBook-Air:hellodebug.com maximveksler$ git up
Fetching origin
Warning: Permanently added 'github.com,192.30.252.128' (RSA) to the list of known hosts.
You're not currently on a branch. I'm exiting in case you're in the middle of something.

git up won't talk to us, that's cool. I don't really need it anyway.

Maxims-MacBook-Air:hellodebug.com maximveksler$ git checkout master
Warning: you are leaving 2 commits behind, not connected to
any of your branches:

  e9e202c no border
  b5cb3e4 Back to not fucking it up

If you want to keep them by creating a new branch, this may be a good time
to do so with:

 git branch new_branch_name e9e202c

Switched to branch 'master'
Your branch is up-to-date with 'origin/master'.

What? No! Come back commits, I love you.

Maxims-MacBook-Air:hellodebug.com maximveksler$ git status
On branch master
Your branch is up-to-date with 'origin/master'.
nothing to commit, working directory clean

Lost! Forever? I hope not..

Maxims-MacBook-Air:hellodebug.com maximveksler$ git reflog
7f9dd75 HEAD@{0}: checkout: moving from e9e202c4703939064e099b735ceeb6b78dc7933a to master
e9e202c HEAD@{1}: commit: no border
b5cb3e4 HEAD@{2}: commit: Back to not fucking it up
54561ed HEAD@{3}: checkout: moving from master to 54561ed320633e72bb35a7ab668a9996e6ffca8f
7f9dd75 HEAD@{4}: commit: Imagine a Supercomputer Helping You Fix Bugs Faster
54561ed HEAD@{5}: commit: highcharts tweaks

OK, so they are somewhere in the wild, but how I get them back? It's too early to say goodbye.

HELP?

Answer 1

To push your changes made on detached HEAD to origin/master (or to different branch), try:

git push origin HEAD:master

If you got warning, make sure you're up to date with origin (you may try to pull it first). Although if you're amending commits or and you're sure your changes are the latest, you can push it with force (-f/--force). It's not recommended, unless you know what you're doing (like rebasing).

Answer 2

You can merge the upstream master branch with the -s ours strategy (or -s theirs when you are on master). So, you do not break the history (like git reset --hard or rebase operations) but keep the working tree.

This method is especially helpful when a single git revert does not suffice (e.g. when there are merges between the good and the upstream branch).

Answer 3

Since you already pushed the commit 7f9dd753d39fd65b4272af713ef9c07a9f84f016 I would recommend to do a git revert.

First checkout your master and do

git revert 7f9dd753d39fd65b4272af713ef9c07a9f84f016

This creates a new commit on top of master that reverts the changes introduced in 7f9dd753.

Now checkout the fix you made as a new branch (You can see the commit id in the reflog e9e202c HEAD@{1}: commit: no border)

git checkout -b myFix e9e202c 

Rebase the myFix changes on master.

git rebase master

Switch back to master and fast forward it to the rebased myFix branch.

git checkout master
git merge myFix

Now you can delete the myFix branch and push the master.

git branch -D myFix
git push origin master

Answer 4

If the fix is reasonable fast to do I would do it again but in a different way, starting from your bad commit

git reset --hard HEAD^ # brings your entire master branch and working copy back to where it worked
git reset origin/master # brings your HEAD pointer back to origin/master but leaves your working copy with the working code
# fix code
git commit -a -m'try to not fuck it up'
git push

Another way would be to revert the bad commit, to clearly show that it was bad, and then make fixes after that

git revert HEAD^
# fix code
git commit -a -m'better code this time'
git push # pushes two commits, the revert and the new code

If you want to keep the code you've already got on a detached head you should be able to cherry-pick it in both of the flows above, instead of fixing the code, just git cherry-pick b5cb3e4.

Good luck.