concurrent access to share site using the Share web UI and webdav by two users break the copy.

concurrent access to share site using the Share web UI and webdav by two users break the copy. tkt 26346

This is a variant of ALF-6918 but with two users

How to reproduce?
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1) create a 3.4.0.1 build1 system (tomcat, linux, mysql)
2) as 'admin' create 2 users 'user1' and 'user2' in alfresco explorer
3) as 'user1' create in Share a site 'site1'
('user1' becomes automatically 'manager' of the site)
4) as 'user2' join 'site1'
5) as 'user1' set 'user2' as 'manager' of 'site1'
6) as 'user1' add a MS Word 2007 'test1.docx' in 'site1' Document Library
7) as 'user1' checkout the 'test1.docx' in Share using 'Edit Offline'
(if a browser 'open with' pop appears just close it)
8) as 'user2' access the site1 Document Library using Netdrive and open 'test1 (Working Copy).docx' modify it and save it.
top

Results:
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Go back to Share and try to unlock the locked document or refesh the page two files appear (no lock)

A second user can access the working copy through WebDav, amend the file, and upload the changes.
Before fix of ALF-6918, the original file was also affected. it is now locked down which is good, but the second user can still edit the working copy, which disables the ability of the first user to check-in their changes.

see video attached.

Expected Result:
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'user2' cannot edit the copy (or mayve it is even not shown to user2) and cannot check ot again.