Ubuntu Font Rendering Incorrectly in QT/KDE with Hinting "Slight" or "None"

As described here,
http://kubuntuforums.net/forums/index.php?topic=3116117.0

The Ubuntu font that is bundled with Natty in Beta 1 of Kubuntu renders in bold in KDE and QT apps when using either "none" or "slight" as hinting style, while "medium" or "full" correctly renders the font in regular weight. This applies both to sub-pixel rendering and regular anti-aliasing.

The issue seems to have happened around the Beta 1 mark, as replacing /usr/share/fonts/ with the one from a previous build (not sure which exactly, but pre-beta anyway) fixes the problem.

GTK rendering is unaffected (Firefox renders the Ubuntu font in regular weight).

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: xorg 1:7.6+4ubuntu3
ProcVersionSignature: Ubuntu 2.6.38-8.41-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: kwin
DRM.card0.DP.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.DP.2:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.HDMI.A.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
DRM.card0.LVDS.1:
 status: connected
 enabled: enabled
 dpms: On
 modes: 1366x768
 edid-base64: AP///////wAGrywQAAAAAAESAQOAHRB4Crplm1lUniYaTVIAAAABAQEBAQEBAQEBAQEBAQEBIBxWgFAAIzAwIDYAJaQQAAAYAAAADwAAAAAAAAAAAAAAAAAgAAAA/gBBVU8KICAgICAgICAgAAAA/gBCMTMzWFcwMSBWMCAKALw=
DRM.card0.VGA.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes:
 edid-base64:
Date: Sun Apr 10 23:07:30 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: kubuntu
EcryptfsInUse: Yes
GraphicsCard:
 Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Device [1043:1862]
   Subsystem: ASUSTeK Computer Inc. Device [1043:1862]
InstallationMedia: Kubuntu 11.04 "Natty Narwhal" - Beta 1 amd64 (20110329.1)
MachineType: ASUSTeK Computer Inc. UL30A
ProcEnviron:
 LANGUAGE=en_US:en
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-2.6.38-8-generic root=UUID=ee12fef7-92d5-4228-9933-2997a17f0555 ro rootflags=subvol=@ quiet splash vt.handoff=7
Renderer: Unknown
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/28/2009
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 212
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: UL30A
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: ATN12345678901234567
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr212:bd12/28/2009:svnASUSTeKComputerInc.:pnUL30A:pvr1.0:rvnASUSTeKComputerInc.:rnUL30A:rvr1.0:cvnASUSTeKComputerInc.:ct10:cvr1.0:
dmi.product.name: UL30A
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.
version.compiz: compiz N/A
version.ia32-libs: ia32-libs 20090808ubuntu11
version.libdrm2: libdrm2 2.4.23-1ubuntu6
version.libgl1-mesa-dri: libgl1-mesa-dri 7.10.1-0ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.1-0ubuntu3
version.xserver-xorg: xserver-xorg 1:7.6+4ubuntu3
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu6
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu6