[Evolution] disabling junk plugin

[Carl Schaefer <schaefer trilug org>]

With 3.12.3 on Arch linux, when I mark a message as junk (or not junk)
an error box displays over part of the message pane, saying:

Error while Unknown background operation.
Failed to spawn Bogofilter (/usr/bin/bogofilter --register-spam --unicode=yes): Failed to execute child 
process "/usr/bin/bogofilter" (No such file or directory)

I don't have Bogofilter or SpamAssassin installed, but unfortunately on
the Junk tab in Mail Preferences there is not a "none" option for "Junk
filtering software".  If I use dconf-editor to set
org.gnome.evolution.mail.junk-default-plugin to "none" the error box
stops being displayed (at least until the Junk tab is opened again, at
which point the value of junk-default-plugin resets to "Bogofilter").

Should there be a way to disable the junk plugin, even when evolution is
built to support it?  I use the Junk operation to quickly refile
messages (I process them in bulk later), so IMO it's still useful even
without a plugin.

Carl