Dmitrijs Ledkovs wrote : "Can you please confirm in which cases is this bug not present"
I can't confirm for 11.04 (It's not interesting to me) and for Win7 (don't have) but i just made a successful Wubi-install of Oneiric (11.10) in Win8 : see wubi-11.10-rev245.log attached
Before that, the previous installation of Ubuntu 12.04 was removed and hibernation was enabled in Win8.
After install, extract of the result of the "mount" command :
/dev/sdb1 on /host type fuseblk (rw,nosuid,nodev,relatime,user_id=0,group_id=0,allow_other,blksize=4096)
Checking of rights on hiberfi.sys :
ls -la /host/hiberfil.sys
-rwxrwxrwx 1 root root 3435544576 2012-08-28 10:58 /host/hiberfil.sys
So, the bug is not present in a Wubi-install of Oneiric.
Note : wubi-11.10-rev245.log contain a line "IOError: [Errno 13] Permission denied: 'J:\\wubildr'" but it is a false problem (J : dont exist)