Attempted fixes for #1117, where post_author twitter account is used instead of coauthor

[benlk]

This PR is a shot in the dark. I don't know why the behavior described in #1117 is happening.

Changes

• makes sure that $via is '' before trying to use the post_author's Twitter handle
• Doesn't display the post_author's Twitter handle in the "More" social menu if Co-Authors Plus is present and active.

Why

Because #1117 and http://jira.inn.org/browse/WE-87

[benlk]

Tried to replicate with http://womensenews-largoproject-org.largoproject.staging.wpengine.com/2016/01/test-partners-post/

• created by user benlk with the twitter username benlkeith
• guest author alexandra-muck with twitter username testuser
• site twitter user set to http://twitter.com/womens_enews

Not reproducing the bug. :(

[aschweigert]

did we try clearing the cache on production?

[benlk]

Note for the future:

What we think happened here was that Co-Authors Plus' query for author pages was cached.

if ( function_exists( 'coauthors_posts_links' ) && !isset( $values['largo_byline_text'] ) ) {
    $coauthors = get_coauthors( $post->ID );

If that query is cached, then the author objects returned are wrong, and therefore the twitter handle returned is wrong, and therefore the "via" text is wrong.

So the solution is to reset the cache on production.

[benlk]

I think we should still merge this fix, because it does prevent the wrong Twitter handle from being output in the "More" menu.