yeoman/grunt-usemin — pull request #323 by vlajos (2014-03-21 11:19:16+00:00)
Title: fix #307 - grunt-watch spawn:false compatibility fix

if the newly generated part is already in the config file with the same destination update only the source part, instead of add the whole block again. This way the same targets won't be regenerated multiple times if usemin is called multiple times which can happen with grunt-watcher spawn:false mode.