Automatically Add .gitignore Files

I frequently forget to add .gitignore files when creating new .gitignore files.

I'd like to request a command-line option to always add .gitignore files (or, more generally, always add files that match a given file specification).

Replicate

0. git init ...
1. echo "*.bak" >> .gitignore
2. touch file.txt
3. git add file.txt
4. git commit -a -m "..."
5. git push origin master

Expected Results

The .gitignore file is also added to the repository. (This is probably the 80% use case.)

Actual Results

The .gitignore file is not added to the repository.

Additional Details

At step 4, there should be a prompt, warning, or (preferably) either a command-line or configuration option to add the .gitignore file prior to commit, automatically. Such as:

git commit --include-all-gitignore-files -a -m "..."

Or:

echo "**/.gitignore" >> .git/config/add-before-commit