managesieve: Out-of-Office strips angle brackets from message body

[maxtruxa]

The managesieve plugin (incorrectly) strips angle brackets from the message body (reason).

To reproduce:

• Enable the managesieve plugin by adding $config['plugins'] = array( 'managesieve' ); to Roundcube's config and configure it to connect to a ManageSieve server.
• Add $config['managesieve_vacation'] = 1; to the plugin's config to enable the interface for out-of-office responses.
• Log into Roundcube and go to Settings > Out of Office.
• Input a Body containing angle brackets (i.e. foo <bar> baz).
• Hit Save.
• Reload the page.
• The angle brackets and anything between them are now gone. (i.e. foo baz).

That it's actually Roundcube that butchers the message body can be verified by turning on managesieve_debug. Logs show that the message sent to the server was already stripped of the angle brackets.

[29-Jul-2020 15:57:06 +0200]: <lg8gof5f> C: PUTSCRIPT "roundcube" {389+}
require ["date","fileinto","relational","vacation"];
# rule:[Out of Office]
if allof (currentdate :zone "+0200" :value "ge" "date" "2020-07-29", currentdate :zone "+0200" :value "le" "date" "2020-07-29")
{
        vacation :addresses ["[email protected]"] "foo  baz";
}