Revert "Pass HOME and PATH env vars from riff CLI to docker"

The parent's process environment should be inherited by default. (It may not
have been, but that's another matter.)

This reverts commit 3931b32.

Breaks #586

riff-cli/pkg/docker/docker_utils.go

@@ -21,7 +21,6 @@ import (
 	"strings"
 	"bufio"
 	"os/exec"
-	"os"
 )
 
 //go:generate mockery -name=Docker -inpkg
@@ -49,7 +48,9 @@ func DryRunDocker() Docker {
 }
 
 func (d *processDocker) Exec(command string, cmdArgs ... string) error {
-	cmd := createDockerCommand(command, cmdArgs...)
+	commandAndArgs := append([]string{command}, cmdArgs...)
+
+	cmd := exec.Command("docker", commandAndArgs...)
 	stdout, _ := cmd.StdoutPipe()
 	stderr, _ := cmd.StderrPipe()
 	cmd.Start()
@@ -58,24 +59,6 @@ func (d *processDocker) Exec(command string, cmdArgs ... string) error {
 	return cmd.Wait()
 }
 
-func createDockerCommand(command string, cmdArgs ...string) *exec.Cmd {
-	commandAndArgs := append([]string{command}, cmdArgs...)
-	cmd := exec.Command("docker", commandAndArgs...)
-	cmd.Env = createEnv("HOME", "PATH")
-	return cmd
-}
-
-// create a process environment based on the environment variables with the given keys
-func createEnv(keys ... string) []string {
-	env := []string{}
-	for _, key := range keys {
-		if value, set := os.LookupEnv(key); set {
-			env = append(env, fmt.Sprintf("%s=%s", key, value))
-		}
-	}
-	return env
-}
-
 // to print the processed information when stdout gets a new line
 func print(scanner *bufio.Scanner, prefix string) {
 	scanner.Split(bufio.ScanLines)