I pushed fix.

I'll look into it again. I also noticed that it didn't work for me when I tried to use it for a merge commit.

I just tried using the hook and it didn't work for me.
After installing it, I added a dummy file in an issue branch and commited the change with
  git commit -m "haaands"
The log shows the commit message as
  "haaands [issue923] haaands"

So the original message shows up before the message we want.

Also, to make the installation easier, it would be great if the hook was already executable. I think we discussed this in the code review.

As discussed live with Malte and Jendrik, I merged this one.

I updated the pull request: https://github.com/aibasel/rik-downward/pull/1/files

I had a look at the change and left some comments. The current hook automatically prepends the branch name to any commit message. I suggest to extend this, so it checks if the commit message already starts with the correct string and doesn't add it in this case (so we don't end up with "[main] [main] message").

It would also be nice to add a prepare-commit-msg hook that adds the string if you call "git commit" without the "-m" option. This way it would show up in the editor and it would remove the uncertainty about who is responsible for adding it.

Finally, issue973 lists some checks we want to do about what parents a commit can have (e.g., a commit on main, has to have another commit on main as its first parent.), in particular, this is in msg9380 and msg9376. Could you also add hooks for this?

A WIP solution is avaiable at https://github.com/aibasel/fast-downward-
issue968/pull/1/files

This currently includes an installation script and a hook which keeps all 
hooks up-to-date automatically. This might be entirely over-engineered and 
simply including the hook and requiring users to manually copy it into their 
.git/hooks folder and repeat this whenever some hook changes or gets added 
might suffice.

(Moving message from summary to change note.)

We want to automatically prepend the branch name to all commits so we know to 
which branch a commit was made in hindsight.