Fix possible regression when resolving conflicts

1. Launch Drive
2. Login valid credentials
3. create a file on the client side (RTF file for example)
4. wait for sync completion
5. check the file is created on server side
6. quit the Drive client
7. replace the file with another one in the Document (server side)
8. edited the RTF file (client side) and save it
9. when starting the client I there is a conflict alert
10. choose "use local" to resolve it.
11. wait for end of synchronization completion
12. check the server, the file has not been uploaded

This works fine with 2.1.707 but not with 818