It seems that logo has been hard-coded somewhere, and there're only there options that are related to logo :
logoText = "Zzo" # Logo text that appears in the site navigation bar.
logoType = "short" # long, short -> short: squre shape includes logo text, long: rectangle shape not includes logo text
logo = true # Logo that appears in the site navigation bar.
It seems that logo has been hard-coded somewhere, and there're only there options that are related to logo :
How can I set a custom logo ?