The reply-pill fix split the body on a leading "> " so the strip would not
rewrite the "> <@bot:srv>" pill. That keyed the exemption on the body shape,
not on the relation: a hand-typed blockquote in a plain (non-reply) message
that mentions the bot inside the quote reached the agent with the raw
"@hermes:example.org" text, which main used to strip. Split around the quote
only when m.relates_to carries m.in_reply_to; otherwise strip the whole body.
Review finding: quote-block exemption keyed on body.startswith('> ') instead of m.in_reply_to.
060e2a4286