Fix cherry pick preview

[carlfriedrich]

The preview on cherry pick was accidentally broken since we included the +/- information in the commit list. Fix this by using the correct string index.

Check list

• [x] I have performed a self-review of my code
• [ ] I have commented my code in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation

Description

Type of change

• [x] Bug fix
• [ ] New feature
• [ ] Refactor
• [ ] Breaking change
• [ ] Documentation change

Test environment

• Shell
  • [x] bash
  • [x] zsh
  • [x] fish
• OS
  • [x] Linux
  • [ ] Mac OS X
  • [ ] Windows
  • [ ] Others:

[cjappl]

Thanks for catching!