how to check for uncommitted/unstaged changes on remote side before pushing

Hi,

I am trying to abuse git as a code distribution channel and would like to be able to trigger redistribution just by git push.

The idea is to push to a remote to the branch that is currently checked out followed by a git reset --hard in the post-receive hook. I have already figured out that I need to set receive.denyCurrentBranch to ignore to be able to push to the currently checked out branch.

I am also aware that it is a good idea to git pull before git push just in case there were local commits on the remote.

git reset --hard will unconditionally throw away local uncommitted changes. I would like to detect this situation on the remote and abort the receive progress. But my pre-receive hook does not work as intended. Here is my code:

#!/bin/bash

echo "this is the pre-receive hook on $HOSTNAME"

if [ "$(git status --porcelain | wc -l)" -ne 0 ]; then
  echo "there are uncommitted changes"
  echo "PWD=$PWD"
  echo "git status --porcelain"
  git status --porcelain
  echo "end git status"
  exit 1
fi

When I invoke my hook from the remote, everything is fine:

mh@jessie:~/.stdacct$ .git/hooks/pre-receive
this is the pre-receive hook on jessie
there are uncommitted changes
PWD=/home/mh/.stdacct
git status --porcelain
 M dotfiles/.bashrc
 M hooks/pre-receive-hook
?? hooks/pre-receive-hook~
end git status
mh@jessie:~/.stdacct$ 

However, the output is different when invoked during a push:

[7/504]mh@swivel:~/git/stdacct$ git push jessie
Counting objects: 4, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (4/4), 363 bytes | 0 bytes/s, done.
Total 4 (delta 3), reused 0 (delta 0)
remote: this is the pre-receive hook on jessie
remote: there are uncommitted changes
remote: PWD=/home/mh/.stdacct/.git
remote: git status --porcelain
remote: ?? HEAD
remote: ?? ORIG_HEAD
remote: ?? config
remote: ?? description
remote: ?? hooks/applypatch-msg.sample
remote: ?? hooks/commit-msg.sample
remote: ?? hooks/post-receive
remote: ?? hooks/post-update.sample
remote: ?? hooks/pre-applypatch.sample
remote: ?? hooks/pre-commit.sample
remote: ?? hooks/pre-push.sample
remote: ?? hooks/pre-rebase.sample
remote: ?? hooks/pre-receive
remote: ?? hooks/prepare-commit-msg.sample
remote: ?? hooks/update.sample
remote: ?? index
remote: ?? index.lock
remote: ?? info/
remote: ?? logs/
remote: ?? objects/
remote: ?? refs/
remote: end git status
To ssh://jessie/home/mh/.stdacct
 ! [remote rejected] jessie -> jessie (pre-receive hook declined)
error: failed to push some refs to 'ssh://jessie/home/mh/.stdacct'

It looks like the hook thinks that it is invoked inside the .git/hooks directory which is not considered part of the repository.

What is going wrong here?

If my entire approach is wrong, what is the recommended way to prevent a repository with unstaged or uncommitted changes from being pushed to?

Greetings Marc