The user gets a popup with the Blender versions for which they have
synced settings, can select one, and it'll pull those settings in.
There is an issue, though: the PULL action operator doesn't report to
the GUI the way it's written now. Will look at that later.
Instead, an error is shown that there are no synced settings. This will
have to be replaced, allowing the user to select from settings that
are available for other Blender versions.
A POST to create a new node didn't invalidate the preceeding GET on
/nodes to find whether the node already exists. As a result, the negative
answer was cached, and new nodes were created even though the node
already existed.
