Editing a post destroys / mangles new line whitespace

Am I the only one seeing this?  When editing a post the newlines either get concatenated or replaced with double-returns.  It's all over the place.  

To duplicate:

- Post something with multiple paragraphs.  

- Edit it.  

- And then observe that the return-line whitespace has now completely changed.

- Now try to re-make the paragraph breaks

- Commit the edit

- Observe the wonderful results!

It's painful how poorly tested these website changes are.