Did George Harrison play on Donovan's Sunshine Superman?

The rumor has circulated for years ... in 1966 George Harrison
recorded a guitar track for friend and companion Donovan's
signature song, "Sunshine Superman."  Or did he?  Dan
Markus put the question to Donovan, who in turn puts the rumor to
rest once and for all.  (For more from Dan Markus' Wax
Museum, visit http://danmarkuswaxmuseum.com)