Code-review polish on admin_coverage_test.go:
- Replace inline artist-seed SQL with the seedArtist helper used
across the rest of the api test suite (admin_covers_test.go,
likes_test.go, me_history_test.go, admin_quarantine_test.go).
- Rename the cover_art_source pointer locals from none/sidecar/mbcaa
to sourceNone/sourceSidecar/sourceMbcaa so they don't read like
zero-value identifiers.
bvandeusen
97cca4411a