--gui::
When 'git-mergetool' is invoked with the `-g` or `--gui` option
the default merge tool will be read from the configured
- `merge.guitool` variable instead of `merge.tool`.
+ `merge.guitool` variable instead of `merge.tool`. If
+ `merge.guitool` is not set, we will fallback to the tool
+ configured under `merge.tool`.
--no-gui::
This overrides a previous `-g` or `--gui` setting and reads the