cus-dep.el broken
cus-dep.el tries to be smart and only evaluates the defcustoms,
defgroups, etc in the files it loads however. If the defcustom
contains a :set function that is defined locally this breaks.
cus-dep.el does not evaluate the defun and therefore the function is
undefined when the defcustom is evaluated.
cus-dep should either just 'load' the file or redefine
custom-add-variable and friends to not try to call the functions.
Jan