Problem if "vm-summary-arrow" is not a 2-character-long string

[Alain Cochard]

Hello.  I used to have

(setq vm-summary-arrow "")

with

   VM version 8.1.2
   GNU Emacs 24.5.1
   Fedora 23

Now (with a new computer) and

   VM version 8.2.0b
   GNU Emacs 27.2
   Fedora 34

the INBOX summary is messed up if, e.g., I delete a message.

Before deleting the message, il looks like:

 73       Alain.Cochard@unistra.fr  Mon 11 Oct 2021 18:40  test png 
 74    R  Amelie                    Mon 11 Oct 2021 19:11  Re: petit

After deleting the 74th message:

 73       Alain.Cochard@unistra.fr  Mon 11 Oct 2021 18:40  test png
   74  D R  Amelie                    Mon 11 Oct 2021 19:11  Re: petit

If I do not define "vm-summary-arrow" (i.e., using the default), or
define it to any 2-character-long string, there is no problem.

It seems like VM tries to reintroduce a 2-character-long string.  For
example if I use 4 characters, it becomes like this:

     73       Alain.Cochard@unistra.fr  Mon 11 Oct 2021 18:40  test png
   74  D R  Amelie                    Mon 11 Oct 2021 19:11  Re: petit

NB: using vm-undelete-message does remove the 'D', but does not
"unmess" the summary.

Regards,
Alain