Tested at phabricator of the WMF:
At this task I used the wrong preposition, and so I corrected that: here

But my feed shows still the bold content, after purging my cache.

Replication

1. Create a comment
2. Edit the comment
3. Old comment is shown at your user-page-feed

Version

The WMF phabricator version is the phabricator version from 2016-03-03