os.walk follows Windows junctions even if followlinks is False:
>>> import os
>>> appdata = os.environ['LOCALAPPDATA']
>>> for root, dirs, files in os.walk(appdata, followlinks=False):
... print(root)
C:\Users\Test\AppData\Local
C:\Users\Test\AppData\Local\Apple
C:\Users\Test\AppData\Local\Apple\Apple Software Update
C:\Users\Test\AppData\Local\Apple Computer
C:\Users\Test\AppData\Local\Apple Computer\iTunes
C:\Users\Test\AppData\Local\Application Data
C:\Users\Test\AppData\Local\Application Data\Apple
C:\Users\Test\AppData\Local\Application Data\Apple\Apple Software Update
C:\Users\Test\AppData\Local\Application Data\Apple Computer
C:\Users\Test\AppData\Local\Application Data\Apple Computer\iTunes
C:\Users\Test\AppData\Local\Application Data\Application Data
C:\Users\Test\AppData\Local\Application Data\Application Data\Apple
C:\Users\Test\AppData\Local\Application Data\Application Data\Apple\Apple Software Update
C:\Users\Test\AppData\Local\Application Data\Application Data\Apple Computer
C:\Users\Test\AppData\Local\Application Data\Application Data\Apple Computer\iTunes
C:\Users\Test\AppData\Local\Application Data\Application Data\Application Data
C:\Users\Test\AppData\Local\Application Data\Application Data\Application Data\Apple
C:\Users\Test\AppData\Local\Application Data\Application Data\Application Data\Apple\Apple Software Update
C:\Users\Test\AppData\Local\Application Data\Application Data\Application Data\Apple Computer
C:\Users\Test\AppData\Local\Application Data\Application Data\Application Data\Apple Computer\iTunes
C:\Users\Test\AppData\Local\Application Data\Application Data\Application Data\Application Data
[...]
For directory symbolic links, os.walk seems to have the correct behavior. However, Windows 7 (at least) employs junctions instead of symlinks in situations like the default user profile layout, i.e. the "Application Data" junction shown above.
I also noticed that, for junctions, os.path.islink returns False but os.stat and os.lstat return different results.