Unfortunately this is not yet fixed. My users are still getting the overwrite edits message and I just saw it myself. Running 2.8.0.beta2 ( 0f9d31a85e ).
On another note, when trying to upload the first screenshot to meta.discourse I just got an error
PG::UniqueViolation: ERROR: duplicate key value violates unique constraint "uploads_pkey"
Retrying it worked.