internal/v4: fix meta endpoints

We were printing duplicate endpoints in the /meta list.
Also, when retrieving /meta/any with all meta endpoints included,
it was failing because color was not recognised.
Merge pull request #163 from rogpeppe/072-fix-metadata

internal/v4: fix meta endpoints

We were printing duplicate endpoints in the /meta list.
Also, when retrieving /meta/any with all meta endpoints included,
it was failing because color was not recognised.