Metrics filter events do not obey conditionals

Events generated by the metrics filter do not obey conditionals. They get processed by every filter after regardless of conditionals surrounding them.

The config below:
input {
generator {
type => "generated"
}
}

filter {
if [type] == "generated" {
metrics {
meter => "events"
add_tag => "metric"
}
}

if [type] == "should_never_happen" {
mutate {
add_tag=> ["should_never_be_added"]
}
}
}

output {
if "metric" in [tags] {
stdout {
debug => true
}
}
}

returns this output:

{
"@version" => "1",
"@timestamp" => "2013-12-30T19:10:22.412Z",
"message" => "ip-10-0-1-36",
"events.count" => 13285,
"events.rate_1m" => 0.0,
"events.rate_5m" => 0.0,
"events.rate_15m" => 0.0,
"tags" => [
[0] "metric",
[1] "should_never_be_added"
]
}
{
"@version" => "1",
"@timestamp" => "2013-12-30T19:10:27.407Z",
"message" => "ip-10-0-1-36",
"events.count" => 54549,
"events.rate_1m" => 2657.2,
"events.rate_5m" => 2657.2,
"events.rate_15m" => 2657.2,
"tags" => [
[0] "metric",
[1] "should_never_be_added"
]
}