On macOS, right click on a link and choose open, opens it in Firefox, not the default browser.macOS: 10.12.4ST: build 3131
Probably a bug in webbrowser module as described in another thread about a similar issue on Linux
Try build 3133 which you can get using the dev builds (https://www.sublimetext.com/3dev). It fixed a related problem for me.
Yes 3133 fixed this issue