correct pathnames for Bundle-type themes.

fixes #1222 probably

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | na
| Fixed tickets | #1222
| Refs tickets  | #1222
| License       | MIT
| Doc PR        | na

I didn't test any of this :grinning: so it would be really great if you could check this @cmfcmf