This bug was introduced in ubuntu-image 0.7. It went unnoticed because if you boot an affected image, the initramfs will auto-resize the rootfs on first boot and you'll never know the partition was undersized.
It also is specific to MBR partition tables, because sfdisk unhelpfully rounds down partition sizes that aren't a multiple of 1MiB.
This bug was introduced in ubuntu-image 0.7. It went unnoticed because if you boot an affected image, the initramfs will auto-resize the rootfs on first boot and you'll never know the partition was undersized.
It also is specific to MBR partition tables, because sfdisk unhelpfully rounds down partition sizes that aren't a multiple of 1MiB.