Add new guard clause in editor_compare_hashes helper function

[suecarmol]

Description

Added a new guard clause in the editor_compare_hashes helper function to check if a user has a block override before sending the email.

Rationale

Emails are being sent when any editor's block status is changed.

Phabricator Ticket

T295608

How Has This Been Tested?

Added new test

Screenshots of your changes (if appropriate):

Types of changes

What types of changes does your code introduce? Add an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Minor change (fix a typo, add a translation tag, add section to README, etc.)

[jsnshrmn]

Looks good, thanks!