Why doesn't deploy from bitbucket work?

Question

PHP

Followed the instructions: jonathannicol.com/blog/2013/11/19/automated-git-de...
VPS server, Ubuntu 14.04
I did it on a test subdomain - everything works.
To celebrate, I immediately deleted everything and decided to do the same on the main one, with improvements.
Did not work out.
Now back to a simple version with a test subdomain.
And so, there is a private repository on bitbucket, 2 Deployment keys have been added:
1. For the username user (located in /home/username/.ssh)
2. For the www-data user (Apache runs under it, lies in /var/www)
There is only 1 file in the repository - index.php
Then I follow strictly according to the instructions, changing only the paths in bitbucket-hook.php (I also tried to change for git). Well, I only have a branch master
After executing the commands

git clone --mirror [email protected]:username/deploy.git
cd deploy.git
GIT_WORK_TREE=/var/www/deploy.example.com git checkout -f master

Index.php appeared in the /var/www/deploy.example.com folder
, and rights were also given (already tried this way and that) to the folder with the site and to the repository:

sudo chown -R username:www-data /var/www
sudo chown -R username:www-data deploy.git

Thus, for all the necessary folders, the owner is specified as:
Owner/group
username/www-data
I clone the repository on the computer, make changes, send a commit to the server...
Everything reaches bitbucket-hook.php, the log is written.
Then I noticed the following happens:
1. In the folder deploy.git, the owner of the index file changes to www-data/www-data
2. In the folder /var/www/deploy.example.com, the owner of the index.php file changes to www- data/www-data
And that's it, no changes.
If you now execute the commands that are written in bitbucket-hook.php

cd ~/deploy.git
git fetch
GIT_WORK_TREE=/var/www/deploy.example.com git checkout -f

The files will be updated.
At the same time,
/var/www/deploy.example.com/index.php
~/deploy.git/head
~/deploy.git/index
will become owner username/username
After that, if you send the commit again, nothing will happen except for logging with bitbucket...
What to do?
UPD:
I still suspect that www-data has a rights problem, but how to solve it ... I
manually execute the command from the script from www-data

The same command from my user

Answer 1

Thanks to @DancingOnWater for the idea about the broken chown, helped me come up with a solution.
I came to the conclusion that you need to do all the actions from the www-data user, that is: -
generate an ssh key and config for it
- create a folder for the repository and clone the repository the folder with the git repository, and www-data should belong to /var/www (and I specified username/www-data). I checked the solution on a clean installation of the server, everything works. Maybe I'll make a manual if anyone needs it.

Answer 2

I suspect that the repository from which the commit comes and the repository where the bitbuket should be merged is the same