Binary package hint: sysvinit
1) Ubuntu 9.04
2) sysvinit 2.86.ds1-61ubuntu11
3) Mount a vfat medium, like a camera. The file timestamps should reflect the time the photo was taken.
4) The file timestamp is offset by the difference between local time and UTC.
In https://bugs.launchpad.net/ubuntu/+source/sysvinit/+bug/278429 , Scott James Remnant wrote "UTC=yes is the correct and sane default: the only reason you would ever store any other time in your system clock is when dual-booting."
Normally, I would agree with this. However, I have discovered that using UTC as the default for the system clock causes incorrect offsets when mounting vfat media. The kernel uses sys_tz to preadjust timestamps on vfat and other filesystems which use local time instead of UTC. (cf http://lkml.org/lkml/2008/6/27/16 ). This negates the effect of the normal user space translation of UTC timestamps to the user's local time.
I respectfully suggest that this need to compensate for vfat's use of local time forces the kernel to assume that system time is also local time. This in turn means that "UTC=yes" is not the correct default for systems which will be mounting vfat media.
While your interpretation of the problem is incorrect, you have noticed a valid bug. When UTC=yes, we never set set sys_tz because this is set as a side-effect of stepping the system clock when the hardware clock was in localtime.