Update appdatainfo.py

The following is evil. I had to rake my brain for an hour, before I figured out the problem.

def foo():
    l = []
    return l[:]
 
#attr_map = dict.fromkeys(prefixes_unique, foo())
 
attr_map = dict.fromkeys(prefixes_unique, [])
 
for key in attr_map:
    print(key, id(attr_map[key]))