firewall-util: add an assert that we're not overwriting a buffer
... like commit f28501279d2c28fdbb31d8273b723e9bf71d3b98 does for
out_interface.
(cherry picked from commit 0b777d20e9a3868b12372ffce8040d1be063cec7)
Resolves: #1602706
patch_name: 0032-firewall-util-add-an-assert-that-we-re-not-overwriti.patch
present_in_specfile: true
location_in_specfile: 32
squash_commits: true