When 'git-difftool' is invoked with the `-g` or `--gui` option
the default diff tool will be read from the configured
`diff.guitool` variable instead of `diff.tool`. The `--no-gui`
- option can be used to override this setting.
+ option can be used to override this setting. If `diff.guitool`
+ is not set, we will fallback in the order of `merge.guitool`,
+ `diff.tool`, `merge.tool` until a tool is found.
--[no-]trust-exit-code::
'git-difftool' invokes a diff tool individually on each file.