Verified and tested on the latest 8.4.x-dev version. Its working fine as per ...

Verified and tested on the latest 8.4.x-dev version. Its working fine as per the description added on top.
Here are the test observations:
Without applying any patch on 8.4.x-dev :
1. If user try to reset the password for blocked account the error message appears as:
""The username %email has not been activated or is blocked"
2. If user try to create a new account with same username or email-id error message appears as
"The username %name is already taken.
The email address %email is already taken".
Screenshots attached

- Moving it to RTBC as the issue is already fixed on latest version 8.4.x-dev.