tolerate bad path.settings when --help is present

Fixes #5786

logstash-core/lib/logstash/runner.rb

@@ -151,7 +151,9 @@ class LogStash::Runner < Clamp::StrictCommand
       @logger.subscribe(STDOUT)
       @logger.warn("Logstash has a new settings file which defines start up time settings. This file is typically located in $LS_HOME/config or /etc/logstash. If you installed Logstash through a package and are starting it manually please specify the location to this settings file by passing in \"--path.settings=/path/..\" in the command line options")
       @logger.fatal("Failed to load settings file from \"path.settings\". Aborting...", "path.settings" => LogStash::SETTINGS.get("path.settings"), "exception" => e.class, "message" => e.message)
-      exit(-1)
+
+      # abort unless we're just looking for the help
+      return(1) if (["--help", "-h"] & args).empty?
     end
 
     super(*[args])

logstash-core/spec/logstash/runner_spec.rb

@@ -328,4 +328,23 @@ describe LogStash::Runner do
       end
     end
   end
+
+  describe "path.settings" do
+    subject { LogStash::Runner.new("") }
+    context "if does not exist" do
+      let(:args) { ["--path.settings", "/tmp/a/a/a/a", "-e", "input {} output {}"] }
+
+      it "should terminate logstash" do
+        expect(subject.run(args)).to eq(1)
+      end
+
+      context "but --help is passed" do
+        let(:args) { ["--path.settings", "/tmp/a/a/a/a", "--help"] }
+
+        it "should show help" do
+          expect { subject.run(args) }.to raise_error(Clamp::HelpWanted)
+        end
+      end
+    end
+  end
 end