Problem with using backslash to escape semicolon

I have asterisk 1.6.1 beta3 installed on fedora 10 OS. I am trying to manipulate sip header to add a diversion field in the extensions.conf file. But when I use \ with a semicolon, the invite message sent out includes the backslash and this is being rejected by the cisco router.

That is when I add this line to the extensions.conf file:
exten = s,n,SIPAddHeader(Diversion: tel:1001;reason=user-busy;screen=no;privacy=full)

It shows up in invite message as:
Diversion: tel:1001;reason=user-busy;screen=no;privacy=full

Is there a way to send just the semicolon but not the backslash? I need it to show up as:
Diversion: tel:1001;reason=user-busy;screen=no;privacy=full

A bit more googling showed that this is a bug in asterisk that has been resolved -

I am new to asterisk, so I don’t know how to figure out which release contains the fix for this bug. The bug is closed, so can anyone tell me what I should upgrade to, to fix this?