No way to remove dead master branches

[DavidPyke]

Patient Corrections (https://github.com/HL7/fhir-patient-correction) no longer has a master branch but the page still shows it as failing (2 years ago). There is no way to tell it that the branch doesn't exist and that the main is the default. So, building the main branch (or any other branch) doesn't move the IG up on the list.

There should be a way to have a button (or something) to have the page reload the active branch list for the IG

[jmandel]

Thanks -- would love contributions to design for this, but in the meantime I'll accept one-off requests here. I've deleted the master branch.

[vadi2]

Master and main branches are protected from the automatic cleanup by an exemption. Felt a bit risky to remove master branches from the exemption, so I added a separate, concise delete button instead:

This button can delete master and any other branch, except for main.

It's pretty hard to test the setup locally given the integrations the builder has, so I'll leave it with you @jmandel #55