"collapse-all" folder-hook doesn't alway work for default mailbox

[Bill Sun]

Hi all,

I set "folder-hook . 'exec collapse-all'" in my .muttrc. But it not
always works. For example, currently I'm using a keyboard shortcut to
launch mutt(urxvt -e mutt), in this case, the folder-hook doesn't work
for my default mailbox.

However, in these cases listed below, the folder-hook works correctly:
1)First launch a terminal, then type"mutt" in it to launch mutt. In this
  case, the folder-hook also works for default mailbox.
2)Using keyboard shortcut to launch mutt, then enter any folder. In this
  case, the folder-hook doesn't work for default mailbox.

My .muttrc(Only the related part):

    folder-hook . "exec collapse-all"
    folder-hook inbox "set from=f...@bar.com"
    folder-hook !inbox "set from=f...@bar.com"

    set mbox_type=Maildir
    set folder="~/Mail"
    set mbox="~/Mail/inbox"
    set spoolfile="~/Mail/inbox"
    set record="~/Mail/inbox"
    set postponed="~/Mail/postponed"
    mailboxes `find ~/Mail/ -type d -name cur -printf '%h '`

Sorry for my english.
thanks.
Bill Sun