`chezmoi` should print git output when a commit fails

[NinjaLikesCheez]

Is your feature request related to a problem? Please describe.

I found it frustrating to manually debug a git issue when chezmoi couldn't perform a git commit.

Describe the solution you'd like

If committing to the local git repository is failing for some reason - chezmoi should show the user the error instead of silently failing and not logging that an edit with --apply failed to commit and push (for example).

Describe alternatives you've considered

None

Additional context

This could be seen as a bug - but in my case the error was due to my own incompetence - here's a way to replicate it:

• In your ~/.gitconfig add a user signingkey that isn't on the machine and setup gpg.
• make a change to a tracked file with chezmoi edit --apply ~/.some_file
• upon exiting the edit, chezmoi will print nothing and the exit code will be normal - i.e. the user may think that everything worked as expected.
• inspect local git repo to see it's in a dirty state with no commit (because git failed to sign the commit)

For example, this is the output I got:

➜ chezmoi edit --apply ~/.zshrc --verbose

This is what I'd expect:

➜ chezmoi edit --apply ~/.zshrc --verbose
chezmoi: failed to commit change:

<git log here>

[twpayne]

chezmoi already connects the standard input, standard output, and standard error when running external processes, so you should see the output from git.

Can you give an exact sequence of commands that demonstrate this problem on a newly-installed machine?