trouble with 'hostname' in reply-hook

[Louis-David Mitterrand]

Hi,

Using mutt 1.5.20 I have this reply-hook:

reply-hook '~h(X-Original-)?To:....@example.net' "set hostname='example.net'"

But the message-id always has the default 'hostname' (defined earlier in
the ~/.muttrc) not 'example.net'.

Am I missing something?