If git is installed and the current directory is part of a git tree,
then also shows all information from prompt_git.
prompt_devtools(...)devtools_packages()
prompt_devtools() returns the prompt string.
devtools_packages() returns the packages loaded by
devtools/pkgload.
Ignored.
Other example prompts:
new_prompt_powerline(),
prompt_fancy(),
prompt_git(),
prompt_mem(),
prompt_runtime(),
prompt_status()