dissect-image: use right comparison function
fstype can be NULL here.
(cherry picked from commit 4db1879acdc0b853e1a7e6e650b6feb917175fac)
Resolves: #1602706
patch_name: 0030-dissect-image-use-right-comparison-function.patch
present_in_specfile: true
location_in_specfile: 30
squash_commits: true