Hubblestack started life as a Salt execution module meant to be run in a Salt environment. It later evolved into a stand alone daemon by borrowing heavily from the Salt daemon code.
The next stage in this evolution is to remove the salt-ssh dependency from Hubblestack. This dependency is/was essentially all of Salt.
The removal of the Salt dependency is not meant to hide or occlude this relationship. The point is to remove the parts of Salt that Hubblestack nolonger needs (the minion/master relationship, any sort of message bus, various types of template systems, and a few other things) and to avoid having to worry about surprise upstream changes that break Hubblestack.
The Apache license requires, among other things, that we do not remove any copyright or license information from any files copied into Hubblestack from Salt. It may be the case that some parts of Hubblestack are direct or even indirect copies of concepts from Salt that may not have carried a specific license at the time.
Hubblestack has the same LICENSE file as Salt. Should there every be any doubt about the origin of a section of code in the future, please assume that it did come from Salt; and should therefore carry whatever LICENSE restrictions it did in Salt.