I can confirm this problem. After manually fsck the root partition and still get the same initramfs shell I downgraded e2fsprogs and libext2fs2 to the previous versions I found in /var/cache/apt/archives (1.45.2-1) and the system booted again.
- Bug#932854: Missing dependency for initramfs-tools-core Colin Booth
- Bug#932854: Missing dependency for initramfs-tools-... Miguel A. Vallejo
- Bug#932854: Missing dependency for initramfs-tools-... Sven Joachim
- Bug#932854: initramfs-tools-core: Please depend on ... rharwood
- Bug#932854: initramfs-tools-core: Please depend... Sven Joachim

