avoid skips that go twice past max_deferrals not being reduced

Changes

@@ -5,6 +5,10 @@
   * use PG COPY for bulk insert of jobs with prefix
   * support IP prefix enum expansion in scheduler
 
+  [BUG FIXES]
+
+  * avoid skips that go twice past max_deferrals not being reduced
+
 2.039010 - 2018-02-22
 
   [NEW FEATURES]

lib/App/Netdisco/JobQueue/PostgreSQL.pm

@@ -61,10 +61,11 @@ sub jq_warm_thrusters {
       backend => setting('workers')->{'BACKEND'},
     }, { for => 'update' }, )->update({ actionset => [] });
 
+    my $deferrals = setting('workers')->{'max_deferrals'} - 1;
     $rs->search({
       backend => setting('workers')->{'BACKEND'},
-      deferrals => { '>' => 0 },
-    }, { for => 'update' }, )->update({ deferrals => \'deferrals - 1' });
+      deferrals => { '>' => $deferrals },
+    }, { for => 'update' }, )->update({ deferrals => $deferrals });
 
     $rs->search({
       backend => setting('workers')->{'BACKEND'},