bug#52038: Completion for user mailcap entries

[Arash Esbati]

Hi all,

I added some entries to my ~/.mailcap like this (where the action part
is not relevant for this report):

  application/vnd.ms-excel; foo
  application/vnd.openxmlformats-officedocument.spreadsheetml.sheet; bar
  application/vnd.openxmlformats-officedocument.wordprocessingml.document; baz

In Gnus, I take a mail with an attachment (application/octet-stream) and
hit 'e' to view the MIME part externally.  When asked for 'View as MIME
type', I enter 'application/vnd<TAB>' and get the following completions:

Note the \ before the dots and I have to insert a backslash before I can
proceed with completion.  Is this the expected behavior?

This is Emacs 29.0.50 (c7699b9702) on Win10.

Best, Arash