* FIX: Email Send post has already been taken error
Adding a failing test first before coming up with a good solution.
Related: 357011eb3b
The above commit changed
```
PostReplyKey.find_or_create_by_safe!
```
to
```
PostReplyKey.create_or_find_by!
```
But I don't think it is working as a 1-1 replacement because of the
`Validation failed: Post has already been taken` error we are receiving
with this change. Also we need to make sure we don't re-introduce any
concurrency issues.
Reported: https://meta.discourse.org/t/224706/13
* Remove rails unique constraint and rely on db index
I believe this is what is causing `create_or_find_by!` to fail. Because
we have a unique constraint in the db I think we can remove this rails
unique constraint?
* clean up spec wording