I launched the installer from a live USB desktop environment. After a couple of steps I marked the boxes to download updates while installing and install third-party software. To install third-party software I checked the box to turn off secure boot. I entered a seven-character password, but the installer said they did not match (but I know they do)! When I type any password combination, as long as it is less than 8 characters or digits, the installer says Passwords do not match. Any password with 8 characters or above work.
Ubuntu 16.04 Xenial Xerus Daily release 20160229 amd64 with MATE desktop, downloaded from http://iso.qa.ubuntu.com/qatracker/milestones/351/builds
ubiquity:
Installed: 2.21.47
Candidate: 2.21.47
Version table:
*** 2.21.47 500
500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages
100 /var/lib/dpkg/status
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.47
ProcVersionSignature: Ubuntu 4.4.0-8.23-generic 4.4.2
Uname: Linux 4.4.0-8-generic x86_64
ApportVersion: 2.20-0ubuntu3
Architecture: amd64
CasperVersion: 1.367
CurrentDesktop: MATE
Date: Mon Feb 29 14:10:32 2016
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz.efi file=/cdrom/preseed/ubuntu-mate.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu-MATE 16.04 LTS "Xenial Xerus" - Alpha amd64 (20160229)
ProcEnviron:
TERM=xterm
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)
Status changed to 'Confirmed' because the bug affects multiple users.