Mismatched IMG tag in gitlab atom feed

I've just faced with mismatched tag in gitlab atom feed. It happens when someone comments "+1" on merge request. The feed contains IMG tag for "+1" emoji icon, and this tag is not closed.

And since the contents of 'summary' section is not encoded, it makes the feed an invalid.

mentioned in merge request !344 (merged)

Proposed fix in !344 (merged).

Milestone changed to 7.9

Added ~27261 label

Status changed to closed by commit 90aa870c

mentioned in commit e4ac6bbf