Summary:

• When cloning from remote to local or pushing from local to remote, www-data group ownership and 770 permissions are not preserved.
• When pushing local changes to remote, the remote master can't be checkout out.

References:

• stackoverflow question about permissions.
• Using git hooks to run pre- and post- scripts to fix permissions.

• Create two files in a remote folder to simulate the wiki install on the server.

• Change their permissions and ownership to match what's on the server:

  ~/gittest/remote$ ls -l
  total 24
  -rwxrwx--- 1 ptruchon www-data 26 Dec 26 10:20 file1.txt
  -rwxrwx--- 1 ptruchon www-data 26 Dec 26 10:20 file2.txt

• Initialize git:

  git init
  git add .
  git commit -m 'initial commit on remote'
  git log
  commit 0e5ccdedd1c9188996aadad3a8e2be5a319ab789 (HEAD -> master)
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:21:24 2021 -0800
   
      initial commit on remote

• Create a local folder and clone from remote:

  git clone ~/gittest/remote/ ~/gittest/local/

• The log on the local copy looks good:

  ~/gittest/local$ git log
  commit 0e5ccdedd1c9188996aadad3a8e2be5a319ab789 (HEAD -> master, origin/master, origin/HEAD)
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:21:24 2021 -0800
   
      initial commit on remote

• But the www-data group ownership and the 770 permissions weren't preserved:

  ~/gittest/local$ ls -l
  total 24
  -rwxrwxr-x 1 ptruchon ptruchon 26 Dec 26 10:24 file1.txt
  -rwxrwxr-x 1 ptruchon ptruchon 26 Dec 26 10:24 file2.txt

• Change the group back to www-data and permissions back to 770:

  sudo chgrp www-data *; chmod 770 *
  ls -l
  total 24
  -rwxrwx--- 1 ptruchon www-data 26 Dec 26 10:24 file1.txt
  -rwxrwx--- 1 ptruchon www-data 26 Dec 26 10:24 file2.txt

• Edit file1.txt from the local directory.

  ~/gittest/local$ git status
  On branch master
  Your branch is up to date with 'origin/master'.
   
  Changes not staged for commit:
    (use "git add <file>..." to update what will be committed)
    (use "git restore <file>..." to discard changes in working directory)
  	modified:   file1.txt
   
  no changes added to commit (use "git add" and/or "git commit -a")

• Commit changes in git:

  git add .
  git commit -m 'changed file1.txt from local'
  git status
  On branch master
  Your branch is ahead of 'origin/master' by 1 commit.
    (use "git push" to publish your local commits)
   
  nothing to commit, working tree clean
   
  git log
  commit b7d91058fed9fe64c96525a3d0bef56c682ade68 (HEAD -> master)
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:45:41 2021 -0800
   
      changed file1.txt from local
   
  commit 0e5ccdedd1c9188996aadad3a8e2be5a319ab789 (origin/master, origin/HEAD)
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:21:24 2021 -0800
   
      initial commit on remote

• Attempting to push changes to remote while master is still checked out on remote doesn't work:

  ~/gittest/local$ git push origin master
  Enumerating objects: 5, done.
  Counting objects: 100% (5/5), done.
  Delta compression using up to 4 threads
  Compressing objects: 100% (3/3), done.
  Writing objects: 100% (3/3), 329 bytes | 329.00 KiB/s, done.
  Total 3 (delta 0), reused 0 (delta 0)
  remote: error: refusing to update checked out branch: refs/heads/master
  remote: error: By default, updating the current branch in a non-bare repository
  remote: is denied, because it will make the index and work tree inconsistent
  remote: with what you pushed, and will require 'git reset --hard' to match
  remote: the work tree to HEAD.
  remote: 
  remote: You can set the 'receive.denyCurrentBranch' configuration variable
  remote: to 'ignore' or 'warn' in the remote repository to allow pushing into
  remote: its current branch; however, this is not recommended unless you
  remote: arranged to update its work tree to match what you pushed in some
  remote: other way.
  remote: 
  remote: To squelch this message and still keep the default behaviour, set
  remote: 'receive.denyCurrentBranch' configuration variable to 'refuse'.
  To /home/ptruchon/gittest/remote/
   ! [remote rejected] master -> master (branch is currently checked out)
  error: failed to push some refs to '/home/ptruchon/gittest/remote/'

• Workaround is to checkout a temporary branch on remote:

  ~/gittest/remote$ git checkout -b tmp
  Switched to a new branch 'tmp'

• Then push the local changes to remote:

  ~/gittest/local$ git push origin master
  Enumerating objects: 5, done.
  Counting objects: 100% (5/5), done.
  Delta compression using up to 4 threads
  Compressing objects: 100% (3/3), done.
  Writing objects: 100% (3/3), 329 bytes | 329.00 KiB/s, done.
  Total 3 (delta 0), reused 0 (delta 0)
  To /home/ptruchon/gittest/remote/
     0e5ccde..b7d9105  master -> master

• Check status and log from local:

  ~/gittest/local$ git status
  On branch master
  Your branch is up to date with 'origin/master'.
   
  nothing to commit, working tree clean
   
  ~/gittest/local$ git log
  commit b7d91058fed9fe64c96525a3d0bef56c682ade68 (HEAD -> master, origin/master, origin/HEAD)
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:45:41 2021 -0800
   
      changed file1.txt from local
   
  commit 0e5ccdedd1c9188996aadad3a8e2be5a319ab789
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:21:24 2021 -0800
   
      initial commit on remote

• On remote, checkout master and delete the temporary branch

  ~/gittest/remote$ git checkout master; git branch -d tmp
  Switched to branch 'master'
  Deleted branch tmp (was 0e5ccde).

• Status and log both look good:

  git status
  On branch master
  nothing to commit, working tree clean
   
  git log
  commit b7d91058fed9fe64c96525a3d0bef56c682ade68 (HEAD -> master)
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:45:41 2021 -0800
   
      changed file1.txt from local
   
  commit 0e5ccdedd1c9188996aadad3a8e2be5a319ab789
  Author: Patrick Truchon <patoo@rbox.me>
  Date:   Sun Dec 26 10:21:24 2021 -0800
   
      initial commit on remote

• But group ownership of the modified file wasn't preserved

  ~/gittest/remote$ ls -l
  total 24
  -rwxrwxr-x 1 ptruchon ptruchon 50 Dec 26 12:01 file1.txt
  -rwxrwx--- 1 ptruchon www-data 26 Dec 26 10:20 file2.txt