Fix loading pickles

See merge request !1706
12 jobs for fix/zope_text_plain in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.CodingStyleTest-Master

00:06:59

failed ERP5.UnitTest-Master

01:07:55

failed ERP5.UnitTest-Master.Medusa

01:23:40

passed SlapOS.Eggs.UnitTest-Master.Python2

00:12:00

passed SlapOS.Eggs.UnitTest-Master.Python3

00:13:25

failed ERP5.CodingStyleTest-Master

00:31:49

failed ERP5.UnitTest-Master

failed ERP5.UnitTest-Master

01:37:14

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:01

passed SlapOS.Eggs.UnitTest-Master.Python2

00:13:33

passed SlapOS.Eggs.UnitTest-Master.Python3

00:14:00

passed SlapOS.Eggs.UnitTest-Master.Python3