Preview of work-in-progress narratives for translators

[tsibley]

The translators of our 2019-nCoV narratives would benefit from a way to preview their work-in-progress.

Possible solutions:

• ~Use the staging branch of github.com/nextstrain/narratives by frequently merging the topic branches containing translators edits to staging. Requires no code changes.~ This won't work well because narratives are first developed in nextstrain/ncov and then copied to nextstrain/narratives.

• Support a way to specify an alternate Git branch for /community URLs and use on something like /community/nextstrain/narratives@some-other-branch/…. Or possibly via a ?branch= query parameter. The user/repo@branch syntax, however, is common in other places that use Git urls. Requires code changes to CommunitySource in nextstrain/nextstrain.org.

• Something with Heroku review apps?

Option 2 seems like the winner. Slack discussion.

[trvrb]

I like option 2 with user/repo@branch.

[tsibley]

Implemented in #102.