Reading Stdin of spawned Job results in EOF errors

Description of the problem or steps to reproduce

I'm writing a plugin that calls a go binary. When I try to read the stdin from within a spawned process, I'm hit with repeated errors. In my plugin, I use JobSpawn to start the process, and occasionally I'd like to send data to the process with JobSend.

In my spawned job, I have a for loop repeatedly reading from stdin, like so:

package main

import ("fmt"
	"bufio"
	"os")

func main() {
	for {
		reader := bufio.NewReader(os.Stdin)
		arr, err := reader.ReadBytes('\n')
		if err != nil {
			fmt.Print(err)
		} else {
			fmt.Print(arr)
		}
	}
}

Immediately after I spawn the Job, I receive a stream of EOF errors. Additionally, any data I send doesn't seem to make it to the reader - I can't get it to receive anything other than EOF. I'd like the process to only read and print the data when I call JobSend.

Start by tracing the JobSpawn and JobSend entry points and the spawned process's stdin handling; no repository files or tests are named in the issue. Reproduce the Go example and verify that the process does not repeatedly report EOF and receives data only after JobSend is called.