Unexpected behavior around folded block scalars

[dangermike]

I'm seeing doubling of the first newline when using the folding style of block. I can replicate this using yaml.Node{...}, but it seems clearer to parse a string directly. This is my test harness:

package main

import (
	"os"

	yaml "gopkg.in/yaml.v3"
)

func main() {
	src := []byte(`
>
  line 1
  line 2
  line 3
    line 4
`)

	var data yaml.Node
	if err := yaml.Unmarshal(src, &data); err != nil {
		panic(err)
	}

	enc := yaml.NewEncoder(os.Stdout)
	if err := enc.Encode(&data); err != nil {
		panic(err)
	}
	enc.Close()
}```

The result is:

```text
>
    line 1 line 2 line 3

      line 4
      

The second newline between 3 & 4 is, I think a mistake. It becomes clearer if we indent line 2 like so (test):

	src := []byte(`
>
  line 1
    line 2
    line 3
      line 4
`)

This results in:

>
    line 1

      line 2
      line 3
        line 4

This is definitely incorrect.