✅ Guard against inconsequntial CI failures

I haven't reproduced these eriors locally!  But they occur regularly in
CI.  Perhaps there is a race condition?

test/net/imap/fake_server/command_router.rb

@@ -55,7 +55,17 @@ def handler_for(command)
       resp.args.nil? or return resp.fail_bad_args
       resp.bye
       state.logout
-      resp.done_ok
+      begin
+        resp.done_ok
+      rescue IOError
+        # TODO: fix whatever is causing this!
+        warn "connection issue after bye but before LOGOUT could complete"
+        if $!.respond_to :detailed_message
+          warn $!.detailed_message highlight: true, order: :bottom
+        else
+          warn $!.full_message     highlight: true, order: :bottom
+        end
+      end
     end
 
     on "STARTTLS" do |resp|