Forum discussion: https://moodle.org/mod/forum/discuss.php?d=315159
In trying to help a Moodle user achieve a different type of page heading together with a logo, it became increasingly obvious that the new 'classes' renderer function for the context header was not easy to override or indeed change. Also I am not overly convinced that this classes renderer needs to be in the Clean theme at all. If anything it should be in Bootstrapbase and then inherited by Clean and More themes, as it is seemingly a global requirement/ improvement.
There also appears to be a redundant element for the logo/page heading in the clean/lib.php file.