upsert bug?

[strarsis]

When saving a bookshelf record more than one time but with same id, it fails with a postgre sql error:

Unhandled rejection error: insert into "article" ("reference", "title") values ($1, $2) returning "reference" - duplicate key value violates unique constraint "article_reference_unique"
[...]

I prepared a sample for reproducing this issue: https://github.com/strarsis/bookshelf-upsert-issue

[dmlittle]

UPSERT was added to PostgreSQL in version 9.5 but the sample reproduction code is using v9.1. I believe you're not allowed to insert any records with the same unique id more than once in v9.1.

[strarsis]

Thank you for looking into this issue.

Now I tried this also with 9.5/9.6/latest postgres version, but I still get the same error.
You can clone and try it here: https://github.com/strarsis/bookshelf-upsert-issue/tree/postgres_latest

[strarsis]

So this issue also persists with a recent postgresql server.
How can I further debug this?

[strarsis]

So the reason why this fails is that upsert isn't even implemented in underlying knex yet: knex/knex#54