noacl no longer effective under /cygdrive. Still works in other locations

[ilya Basin]

Hi.
For several years I had this in my /etc/fstab.d/$USER

    C: /cygdrive/c none binary,noacl,posix=0,user 0 0

I switched from Cygwin x86 to x64 recently and I noticed that even if `mount` prints this:

    $ mount | grep C:
    C:/cygwin64/bin on /usr/bin type ntfs (binary,auto)
    C:/cygwin64/lib on /usr/lib type ntfs (binary,auto)
    C:/cygwin64 on / type ntfs (binary,auto)
    C: on /cygdrive/c type ntfs (binary,noacl,posix=0,user)

noacl seems to be ineffective:

    basin@basin /cygdrive/c/63/c
    $ rm -f aaa bbb; touch aaa; cmd /c "echo.>bbb"

    basin@basin /cygdrive/c/63/c
    $ cacls bbb
    C:\63\c\bbb BUILTIN\:(ID)F
                NT AUTHORITY\:(ID)F
                BUILTIN\:(ID)R
                NT AUTHORITY\ :(ID)C

    $ cacls aaa
    C:\63\c\aaa NULL SID:(DENY)(special access:)
                         READ_CONTROL
                         FILE_WRITE_EA
                         FILE_EXECUTE
                         FILE_DELETE_CHILD
    ...

There's no suspicious $CYG* env var. I also tried to kill all cygwin processes and umount everything manually. I don't see what's wrong.

Had to change the parent mount point to /cygnoacl in /etc/fstab.d/$USER and from there it works.