Need for there to be at least one successful build for SCMs to show up in the current API, can cause a degradation in some of the features. The example that I am aware of is JENKINS-39482

Would it be possible to provide an API to enable access to the SCMs currently known to the executing Pipeline build, or some alternative?

One defect is not an overwhelming evidence of a need for such API, but I wanted to get the idea out there.