Better multiline handling for Jenkins console logs

* modules/openstack_project/templates/logstash/agent.conf.erb: Treat any
line not beginning with a timestamp in Jenkins console logs as belonging
to the previous log message. This keeps timestamps sane for messages
that do not have timestamps.

Change-Id: I5959e766c28efebbd6c44567262beb63ad3a0a8e
Reviewed-on: https://review.openstack.org/26777
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins

modules/openstack_project/templates/logstash/agent.conf.erb

@@ -18,17 +18,13 @@ filter {
   }
   multiline {
     type => "jenkins_console"
-    pattern => "^\"'$"
-    what => "previous"
-  }
-  multiline {
-    type => "jenkins_console"
-    pattern => "^Extracting templates from packages"
+    negate => true
+    pattern => "^%{DATESTAMP} \|"
     what => "previous"
   }
   grok {
     type => "jenkins_console"
-    pattern => [ "%{DATESTAMP:logdate} \| %{GREEDYDATA:logmessage}" ]
+    pattern => [ "^%{DATESTAMP:logdate} \| %{GREEDYDATA:logmessage}" ]
     add_field => [ "received_at", "%{@timestamp}" ]
   }
   date {