With file-4.13, I can issue: # file -s /dev/hda? and I get a nice report on the type of file system on each partition type. /dev/hda2: Linux/i386 swap file (new style) 1 (4K pages) size 52210 pages With file-4.15, the same command puts out nothing useful (it just lists the partitions with no text). /dev/sda2: I suspect that this needs to be pushed upstream. Meanwhile, 4.15 should probably be masked.
file-4.14 works too so that should help narrow down the differences
upstream sent me a fix which is in 4.15-r1 now, thanks for the bug