Fix potential mem leak in IP frag reassembly.

Reported by Coverity, but it's not a typical code path.
Fix a couple nits reported by Coverity.

An unnecessary null pointer check and uninitialized scalar fields.
Don't expect these to be actual problems, but easy enough to fix in
order to silence Coverity.
Change #types description of sets to set

Addresses BIT-1163
Merge remote-tracking branch 'origin/topic/jsiwek/coverity'

* origin/topic/jsiwek/coverity:
  Fix a couple nits reported by Coverity.
  Fix potential mem leak in IP frag reassembly.

BIT-1174 #merged
Merge remote-tracking branch 'origin/topic/bernhard/ticket-1163'

* origin/topic/bernhard/ticket-1163:
  Change #types description of sets to set

BIT-1163 #merged