Broken links to approver's avatars in emails

Approver avatars are not shown in "merge request approved" emails.

When copying the link to image, the result is:

https://ci4.googleusercontent.com/proxy/redacted_long_base64_string#http:///uploads/system/user/avatar/1203107/avatar.png

Please note the empty domain in http:/// part. When replacing that part with http://gitlab.com/, the user avatar indeed shows correctly.