Custom HTML quotes problem (PHP escape characters)

Glancing through the forum posts and surprised I didn’t see it previously addressed:

I attempted to insert an image tag into the custom HTML field:
<img src="https://i.example.com/email_15x11.png" alt="" />

On settings page save, that tag is then displayed like this (note single quotes):
<img src='https://i.example.com/email_15x11.png' alt='' />

and the HTML displayed on the post page is broken because of the escape characters:
<img src=\'https://i.example.com/email_15x11.png\' alt=\'\' />

Thoughts?