When looking for related posts, Jekyll was indexing `Jekyll::Post`
objects, but finding related posts based on `Jekyll::Post#content`. This
caused two problems:
1. Ruby 2.2 will warn on == if <=> throws an exception (and future Ruby
versions will surface that exception). Because `String`s can't be
compared with `Jekyll::Post`s, this warning was appearing all the time
while searching for related posts.
2. LSI won't return a post itself when searching for related posts. But
LSI could never tell that we were searching on a post, since Jekyll
passed post content, not a post object. With this fix, we can remove the
`- [post]` from `Jekyll::RelatedPosts#find_related`.
This is a more accurate fix for #3484.
Since we don't actually use the index in getting the related posts from
the tests there's no need to build an index, which can take a long time
if the ruby bindings for the GSL library are not installed.
Ashwin Maroli
Parker Moore
Pat Hawks
XhmikosR
Brint O'Hearn
Jordon Bedwell
Justin Weiss
Arthur Neves
Parker Moore
maul.esel
Anand Narayan
Matt Rogers