[win32] Probably bug: tracking permissions bits on windows

[Alexander Belchenko]

When I'm branching most of bzr development branches published in 
internet I often see that some python script files have status 
"properties changed" (command "bzr st" showed them with asteriks * after 
name).

As I understand that's because Windows have different meaning and 
tracking of permissions bits. Actually on Windows can be two variants of 
this bits: 0666 for rw files, and 0444 for ro files. No execution bit at 
all.

So, make the branch of linux repo on windows with files that have 
execution bits set cause to loss information about execution bits. It 
can be unappropriate in some cases.

I think for cross-platforming it needs to define policy how to track 
permissions bits on different platforms. I think that on Windows bzr 
should not compare bits-by-bits but instead use special comparing 
function. This function could safely translate windows permissions bits 
to internal bzr linux format and vice versa.

Alexander