Earlier quoted context omitted.
How do you deal with version-control noise when updating committed assets?
Just have a separate commit for these. Not really much different from having a commit which updates bower.json or a Gemfile.
$ bower install angular > /dev/null
$ find bower_components/angular/* | xargs wc -l
18 bower_components/angular/angular-csp.css
21463 bower_components/angular/angular.js
210 bower_components/angular/angular.min.js
141 bower_components/angular/angular.min.js.gzip
8 bower_components/angular/angular.min.js.map
7 bower_components/angular/bower.json
48 bower_components/angular/README.md
21895 total
That's 21893 more lines in this diff than the equivalent when using rails-assets.