This is a fixed version of b72a268
* That commit would discard the final key component (so if you set
"config:install_tree:root", it would discard "root" and just set
install tree).
* When setting key:"value", with the quotes, that commit would
discard the quotes, which would confuse the system if adding a
value like "{example}" (the "{" character indicates a dictionary).
This commit retains the quotes.