fixup! erp5_web_service: add also prefix when writing temporary file

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Status Job ID Name Coverage
  External
passed ERP5.CodingStyleTest-Master

01:17:46

failed ERP5.UnitTest-Master

03:56:04

failed ERP5.UnitTest-Master.Medusa

03:54:21

passed SlapOS.Eggs.UnitTest-Master.Python2

00:57:59

passed SlapOS.Eggs.UnitTest-Master.Python3

00:11:33

passed SlapOS.Eggs.UnitTest-Master.Python2

00:10:56

passed SlapOS.Eggs.UnitTest-Master.Python3

00:10:05