BitBucket importer: NoMethodError: undefined method `id' for nil:NilClass

https://sentry.gitlap.com/gitlab/gitlabcom/issues/4287/

NoMethodError: undefined method `id' for nil:NilClass
  lib/gitlab/bitbucket_import/client.rb:15:in `from_project'
    raise Projects::ImportService::Error, "Unable to find project import data credentials for project ID: #{@project.id}"
  lib/gitlab/bitbucket_import/importer.rb:8:in `initialize'
    @client = Client.from_project(@project)
  app/services/projects/import_service.rb:62:in `new'
    class_name.constantize.new(project)
  app/services/projects/import_service.rb:62:in `importer'
    class_name.constantize.new(project)
  app/services/projects/import_service.rb:51:in `import_data'
    unless importer.execute
...
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