[FIX] orm: ignore existing link for operation (4, x) in one2many fields
[FIX] orm: inverting the condition seems to work (don't ask why)
[MERGE] [FIX] orm: Ignore orm (4, *) operations on one2many if link already exists.

Web client returns (4, ) operations for unchanged line in one2many widgets. 
This allows to skip orm write on object where potentially has no access (eg: timesheet line with another user). (opw 599494)