When there is an error using jspm bundle, new save doesn't rebuild

[jonricaurte]

When I am running:

jspm bundle h2 public/h2_assets/build.js --skip-source-maps -wd

And there is an error in one of my files, the build stops and gives an error. When I go and fix that file and press save, the build does not try to restart. I have to Ctrl + C and kill the process and then use the above command again. It would be nice if when you fixed an error, it would rebuild again automatically.

[guybedford]

Let's track this in #1789.

[jonricaurte]

@guybedford sounds good