erp5: Allow other software release provide custom default bt5 to install

See merge request !1534
20 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

00:11:50

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

00:36:54

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

09:32:25

passed SlapOS.Eggs.UnitTest-Master.Python2

00:24:29

passed SlapOS.Eggs.UnitTest-Master.Python3

00:26:30

passed SlapOS.Eggs.UnitTest-Master.Python3Next

00:25:50

failed SlapOS.SoftwareReleases.IntegrationTest-Master

07:14:38

passed SlapOS.Theia.ResilienceTest-Master-ERP5

07:33:52

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:45:14

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

08:14:26

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

00:44:22

passed SlapOS.Eggs.UnitTest-Master.Python2

00:15:01

passed SlapOS.Eggs.UnitTest-Master.Python2

00:28:41

passed SlapOS.Eggs.UnitTest-Master.Python2

00:36:36

passed SlapOS.Eggs.UnitTest-Master.Python3

00:28:00

passed SlapOS.Eggs.UnitTest-Master.Python3

00:18:50

passed SlapOS.Eggs.UnitTest-Master.Python3

00:24:01

passed SlapOS.Eggs.UnitTest-Master.Python3Next

00:15:56

passed SlapOS.Eggs.UnitTest-Master.Python3Next

00:35:23

failed SlapOS.SoftwareReleases.IntegrationTest-Master

09:30:44