Actually, this is for 7.4.3 (Fedora current), but that's not in the list.
The "mdadm" script does not handle the device name "<ignore>" (see https://linux.die.net/man/5/mdadm.conf) as special. This results in an error message in the output. I'm not very good with perl, but I think this should fix the problem.</ignore>
*** /usr/share/logwatch/scripts/services/mdadm 2018-05-21 11:06:11.000000000 +0200
--- /etc/logwatch/scripts/services/mdadm 2018-06-15 14:16:16.044240367 +0200
***************
*** 45,50 ****
--- 45,54 ----
DEV: foreach my $dev (@devices) {
my %mdhash;
+ if ($dev =~ /<ignore>/) {
+ next;
+ }
+
open(MDADM,"mdadm --misc --detail $dev 2>&1 |");
while (<MDADM>) {
if ($_ =~ /cannot open .*: No such file or directory/) {
Changes merged; thanks for submitting them.