Issue Summary

When clicking the "Reply" link for comments in PR emails, users can be shown a comment edit box for resolved comments. They only discover they can't post replies to resolved comments when clicking the "Comment" button to post the comment.

This is reproducible on Data Center: yes

Steps to Reproduce

1. Watch a PR
2. Have another user make a comment on the PR
3. Resolve the comment thread
4. Receive the email about the comment
5. Click the "Reply" link in the email

(For easy testing purposes, you can create a reply link by appending &action=reply to the end of any comment link)

Expected Results

The PR opens with some indication that you can't reply to resolved comments (so users don't write a comment only to find out their time was wasted).

Actual Results

The PR opens to the comment with an edit box. Users can type a reply but are only told they can't post the reply to the comment when they click "Comment", which shows an error saying "Reply cannot be made to resolved thread."

Workaround

N/A