Q:

Git added git HEAD and repo info to files

I have looked around and can't seem to find an actual solution. I've found one or two examples of people with similiar issues but no reasoning to why it happened. Before I show the issue, let me explain what I did:

Pushed a commit from my dev server to the repo to use on my local machine
Checked the dev site and for some reason it now was broken with php errors everywhere

For some reason when I pushed the files it added the following to 20 different files at random locations:
<<<<<<< HEAD
=======
$config['debug'] = '1';
>>>>>>> origin/master

The $config variables are mine but for some reason git shoved content into my files. Any idea why this happened and how to keep it from happening again?

A:

<<<<<<< HEAD
=======
$config['debug'] = '1';
>>>>>>> origin/master

This is unmerged files that you've added to your commit without solving a conflicts. 

Any idea why this happened and how to keep it from happening again?

Perhaps you did pull and git merges upstream commit with your commit. Or you just unfinished your manually merge process.
To keep it from happening again you should better notices a messages from git like this one:
Auto-merging roses.txt
CONFLICT (content): Merge conflict in roses.txt

Then merge conflicts by yourself and add files to the stage.
Anyway, take a look at this article or question about merging conflicts, it could be helpful.

