No mountpoint option when manually partitioning with encrypted volumes

I've noticed this on the quantal-20120924 image for both i386 and amd64
When selecting manual partitioning, and creating an encrypted volume, there is an option on the screen to select the mountpoint, but it is greyed out. To be clear, this doesn't prevent installing successfully, it just means that the user needs to know to select the partition after creating it, click change, and add the mountpoint after creating it. It's somewhat confusing to have an option on the screen that cannot be utilized though.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: ubiquity 2.12.2
ProcVersionSignature: Ubuntu 3.5.0-15.22-generic 3.5.4
Uname: Linux 3.5.0-15-generic i686
ApportVersion: 2.5.2-0ubuntu4
Architecture: i386
CasperVersion: 1.324
Date: Mon Sep 24 21:30:55 2012
InstallCmdLine: file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
LiveMediaBuild: Ubuntu 12.10 "Quantal Quetzal" - Beta i386 (20120924)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)