erp5_core: support "parent" relation in jump

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

00:53:35

failed ERP5.UnitTest-Master

01:42:48

failed ERP5.UnitTest-Zope2

01:54:54

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:47

passed SlapOS.Eggs.UnitTest-Master.Python3

00:15:56

passed Wendelin.UnitTest-Master

00:37:01