erp5_core: Fix unicode bug on ZODB History view.

11 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

00:48:48

passed ERP5.PerformanceTest-Master

00:27:25

failed ERP5.UnitTest-Master

01:28:26

failed ERP5.UnitTest-Master.Medusa

01:45:32

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:59

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:58

passed ERP5.CodingStyleTest-Master

00:38:06

passed ERP5.PerformanceTest-Master

00:27:28

failed ERP5.UnitTest-Master

01:38:35

passed SlapOS.Eggs.UnitTest-Master.Python2

00:12:12

passed SlapOS.Eggs.UnitTest-Master.Python3

00:13:44