Currently after rebase are inline comments still accessible in conversation history, but they don't contain diff (at least 3 lines fo context around commented line), but instead of that they still points to original place that can be totally different code. So basically inline comments in conversation history are useless without diff after rebase.
I think i have seen this issue reported before but, can't find it :/
This is a duplicate of https://pagure.io/pagure/issue/751
Metadata Update from @pingou: - Issue close_status updated to: Duplicate - Issue status updated to: Closed (was: Open)