Buggy output debugging duffsteptest.go

duffsteptest_bug.txt

dlv debug
Type 'help' for list of commands.
(dlv) b main.foo
Breakpoint 1 set at 0x2058 for main.foo() ./code.go:14
(dlv) c
> main.foo() ./code.go:14 (hits goroutine(1):1 total:1) (PC: 0x2058)
     9:	// Expect to be stopped in fmt.Printf or runtime.duffzero
    10:	import "fmt"
    11:	
    12:	var v int = 99
    13:	
=>  14:	func foo(x, y int) (z int) { // c goes here
    15:		fmt.Printf("x=%d, y=%d, z=%d\n", x, y, z) // s #1 goes here
    16:		z = x + y
    17:		return
    18:	}
    19:	
(dlv) s
> main.foo() ./code.go:15 (PC: 0x2087)
    10:	import "fmt"
    11:	
    12:	var v int = 99
    13:	
    14:	func foo(x, y int) (z int) { // c goes here
=>  15:		fmt.Printf("x=%d, y=%d, z=%d\n", x, y, z) // s #1 goes here
    16:		z = x + y
    17:		return
    18:	}
    19:	
    20:	func main() {
(dlv) s
x=99, y=9801, z=0
z=9900
Process 12863 has exited with status 0
(dlv)