You can clone with
HTTPS or Subversion.
Seems the sync task, deletes any posts not found in the folder. Also, would be great to have a way to retrieve existing posts from a blog and having the html files created automatically.
What is your use case that you don't want to delete old posts?
I guess it's that I'm new to grunt and am working on a pre-existing wordpress site. As a developer, I find it easer and quicker to create a bunch of html files in my IDE and run a grunt task, than clicking around the interface of the wordpress admin.
Maybe have something that can parse the exported file from wordpress and create the HTML files from it? Just thinking of ways to avoid the whole, everything in the database, and have the code checked into git somehow.
This isn't something that will be built into grunt-wordpress. This can certainly be built as a separate module on top of node-wordpress though.