There's supposed to be code in partman-basicfilesystems (check.d/mountpoint_fat - never mind the file name) that prevents NTFS being used for system partitions where POSIX semantics are required, too. Although I suppose that if partman were fundamentally confused about the identity of the partition for some reason, or in some cases of pathological manual partitioning, we might have missed something there.
There's supposed to be code in partman- basicfilesystem s (check. d/mountpoint_ fat - never mind the file name) that prevents NTFS being used for system partitions where POSIX semantics are required, too. Although I suppose that if partman were fundamentally confused about the identity of the partition for some reason, or in some cases of pathological manual partitioning, we might have missed something there.