The update_terminal_cmd is interfering with the $? variable. Somehow it
is always 0.
```
caesium@Mac:~/Documents/projects/git/bash-it 0 >export
PROMPT_COMMAND="update_terminal_cwd;set_prompt"
caesium@Mac:~/Documents/projects/git/bash-it 0 >false
caesium@Mac:~/Documents/projects/git/bash-it 0 >true
caesium@Mac:~/Documents/projects/git/bash-it 0 >export
PROMPT_COMMAND="set_prompt;update_terminal_cwd"
caesium@Mac:~/Documents/projects/git/bash-it 0 >false
caesium@Mac:~/Documents/projects/git/bash-it 1 >true
caesium@Mac:~/Documents/projects/git/bash-it 0 >
```
After the fix it is working properly.