Ruby interpreter transitions

Ruby interpreter transitions are done in phases so that (hopefully) unstable is never broken:

phase 0: the new ruby reaches unstable

phase 1: enable both interpreters

ruby-defaults gets uploaded telling gem2deb to build for both the old and the new ruby versions.

phase 2: rebuild/fix

packages get rebuilt/fixed with support for both the old ruby and the new ruby

ideally, what needs to fixed needs to be fixed in a way that it won't need to be fixed again in the next transition.

phase 3: new interpreter becomes the default

ruby-defaults gets uploaded with

this phase may be done in conjunction with the next one

phase 4: old ruby is disabled

ruby-defaults gets uploaded telling gem2deb to stop building for the old ruby, i.e.

this phase may be done in conjunction with the previous one

phase 5: rebuild/fix

packages get rebuilt/fixed to drop support for the old interpreter

phase 6: old ruby gets removed