Rotor was BSD licensed, so I suppose if that’s your definition of a not very open license…
https://en.wikipedia.org/wiki/Shared_Source_Common_Language_...
I have various snapshots of the Rotor 1 and 2 sources around and they have the SSCLI license. There is a file that contains BSD licensed code (pal\rotor_pal.h).
We could go back and check on Codeplex… oh wait.
Thank goodness MS got over their allergy to open source licenses, as they seem to prefer MIT nowadays for their releases.
My apologies for misremembering the details and being snarky. Humble pie eaten and enjoyed. :)