Revert "Merge pull request #7349 from srna/patch-1"

This reverts commit b37b71d887e8521b8992aa6e4f789a38b393e55a, reversing
changes made to 42a1d8083c77d3803320bbbd0ac1559ff32d2519.
Add an avatar_url spec when relative url is set.
Merge branch 'attachment_url_shouldnot_be_overwritten' into 'master'

Attachment url should not be overwritten

Fixes #1786

See merge request !1308