option "defaultBrowser" in ionic.config.json does not work

[koyabr]

operating system: MacOS Sierra 10.12.3
ionic version: 2.1.18

description:

1. type ionic serve --browser "google chrome" in terminal => works as expected.
2. add "defaultBrowser": "google chrome" in ionic.config.json, then type ionic serve in terminal => oops, safari pops out.

I've dug around in the source code of serve.js and project.js, Line 186 of serve.js:

options.defaultBrowser = argv.defaultBrowser || argv.f || project.get('defaultBrowser');

looks fine to me, nothing weird found...

[koyabr]

Update: I've updated ionic to 2.2.1, still no luck.