Emojis don't persist for moved issues

Emojis on comments dont persist when you move an issue from one project to another.

The following issue was moved from CE to EE, but emojis disappeard:

CE https://gitlab.com/gitlab-org/gitlab-ce/issues/38606:

Screen_Shot_2018-01-10_at_4.12.45_PM

EE https://gitlab.com/gitlab-org/gitlab-ee/issues/4543:

Screen_Shot_2018-01-10_at_4.13.17_PM

Expected behavior

Emojis should persist when moving issues.