Use the Afero source fs where relevant

Fixes #2319

commands/hugo.go

@@ -17,7 +17,6 @@ package commands
 
 import (
 	"fmt"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -971,19 +970,7 @@ func isThemeVsHugoVersionMismatch() (mismatch bool, requiredMinVersion string) {
 		return
 	}
 
-	f, err := fs.Open(path)
-
-	if err != nil {
-		return
-	}
-
-	defer f.Close()
-
-	b, err := ioutil.ReadAll(f)
-
-	if err != nil {
-		return
-	}
+	b, err := afero.ReadFile(fs, path)
 
 	c, err := parser.HandleTOMLMetaData(b)
 

commands/undraft.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"github.com/spf13/cobra"
+	"github.com/spf13/hugo/hugofs"
 	"github.com/spf13/hugo/parser"
 )
 
@@ -46,7 +47,7 @@ func Undraft(cmd *cobra.Command, args []string) error {
 
 	location := args[0]
 	// open the file
-	f, err := os.Open(location)
+	f, err := hugofs.Source().Open(location)
 	if err != nil {
 		return err
 	}
@@ -63,7 +64,7 @@ func Undraft(cmd *cobra.Command, args []string) error {
 		return newSystemErrorF("an error occurred while undrafting %q: %s", location, err)
 	}
 
-	f, err = os.OpenFile(location, os.O_WRONLY|os.O_TRUNC, 0644)
+	f, err = hugofs.Source().OpenFile(location, os.O_WRONLY|os.O_TRUNC, 0644)
 	if err != nil {
 		return newSystemErrorF("%q not be undrafted due to error opening file to save changes: %q\n", location, err)
 	}