fix: error type when rejecting session start

[leafty]

Closes #1270.

/deploy renku=feat/private-repository-build renku-ui=feat/build-private-repositories extra-values=dataService.imageBuilders.enabled=true,dataService.imageBuilders.strategyName=renku-buildpacks-v3,dataService.imageBuilders.outputImagePrefix=harbor.dev.renku.ch/renku-ci-private-images-build-public-project/,dataService.imageBuilders.outputPrivateImagePrefix=harbor.dev.renku.ch/renku-ci-private-images-build-private-project/,dataService.imageBuilders.pushSecretName=harbor-public-session,dataService.imageBuilders.pushPrivateSecretName=harbor-private-session,dataService.imageBuilders.pullPrivateSecretName=harbor-private-session,dataService.imageBuilders.nodeSelector.renku.io/node-purpose=user,dataService.imageBuilders.tolerations[0].effect=NoSchedule,dataService.imageBuilders.tolerations[0].key=renku.io/dedicated,dataService.imageBuilders.tolerations[0].operator=Equal,dataService.imageBuilders.tolerations[0].value=user

[RenkuBot]

You can access the deployment of this PR at https://renku-ci-ds-1271.dev.renku.ch

[leafty]

Note (cc @sgaist): the test test/bases/renku_data_services/data_api/test_sessions.py::test_starting_session_with_built_environment needs to be updated/fixed but I don't understand that test nor what it's supposed to test given that the images are not even set (so we don't know if the image is supposed to be public or private...).

[sgaist]

@leafty The image are not set because it is for built environment. This test checks these cases:

• Public repo -> Successful start
• Private repo + pull permission -> Successful start
• Private repo - pull permission -> Start failure
• Private repo without access -> Start failure

TheFakeGitRepositoriesRepository class is the one handling the visibility and pull permission for the testing part.

[leafty]

@leafty The image are not set because it is for built environment. This test checks these cases:

• Public repo -> Successful start
• Private repo + pull permission -> Successful start
• Private repo - pull permission -> Start failure
• Private repo without access -> Start failure

TheFakeGitRepositoriesRepository class is the one handling the visibility and pull permission for the testing part.

Actually, the current logic is incorrect so I have to further change it and will either skip the current tests or re-write them:
The last successful build is the correct source of information to determine the source repository, not the current one set in the build parameters.

[sgaist]

Does the user have the option to select which build they want to use ?

[leafty]

Does the user have the option to select which build they want to use ?

No, you launch with the image from the last successful build.