erp5_base: check consistency when start assignment

   Prevent the user start an inconsistent assignment, since, extra property sheets can include some
   business logic around assignment configuration.
18 jobs for erp5-vifib in 0 seconds
Status Job ID Name Coverage
  External
failed ERP5.UnitTest-erp5-vifib

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passed SlapOS-Master.UnitTest-Master

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failed ERP5.UnitTest-erp5-vifib

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failed ERP5.UnitTest-erp5-vifib

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failed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

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failed SlapOS-Master.UnitTest-Master

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failed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

03:27:00

passed SlapOS-Master.UnitTest-Master

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failed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

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passed SlapOS-Master.UnitTest-Master

02:49:46

failed SlapOS-Master.UnitTest-Master

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failed SlapOS-Master.UnitTest-Master

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