odd status caching behaviour with xls files

I guess that Excel is actually doing some auto-save type operation even if you don't explicitly save. Can you please make a copy of the file while excel is open, and again after you close it, and see if there are any binary differences between them.

Commonly, Excel process effect a change on a .xls file at opening this.
So, on SVN,
1. Open committed Excel file.
2. Run "svn status". << modified
above operation displays "modified", same as BZR.

But, at closed without save, this file is turned back.
So, on SVN,
3. Close this file without saving.
4. Run "svn status". << return to "not modified"
above operation displays nothing, different from BZR.

This is not a generic probrem, but .xls specific one.
In addition, this problem reproduces only on the condition that BZR caches modified time of the file.

Correct operation:
0. *Run "bzr status"* << caching modified time
1. Open committed Excel file.
2. Run "bzr status". << modified
3. Close this file without saving.
4. Run "bzr status". << keep modified!

Once caching modified time, I guess, BZR recognizes file modifying by modified time changing.
But on no caching, by file modification itself.

Modified time changes between #0 to #2, and #2 to #4, so BZR displays "modified".
(as previously described, "Excel process effect a change on a .xls file at opening this.")

On the other hand,
0. *Run "bzr status"* << caching modified time
1. Open committed Excel (not .xlsx but .xls) file.
2. Close this file without saving.
3. Run "bzr status". << No modified files exist.

Modified time doesn't change between #0 to #3.

p.s.
A way to Avoid this behavor is removing "personal or hidden information":
http://office.microsoft.com/en-us/excel-help/remove-personal-or-hidden-information-HP001050332.aspx