Merge pull request git-lfs#257 from github/better-terminal-prompt-message

better error message if you call git-lfs with GIT_TERMINAL_PROMPT

Author: technoweenie

lfs/credentials.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"net/url"
+	"os"
 	"os/exec"
 	"strings"
 )
@@ -90,6 +91,13 @@ func init() {
 			err = cmd.Wait()
 		}
 
+		if exitErr, ok := err.(*exec.ExitError); ok {
+			if exitErr.ProcessState.Success() == false && os.Getenv("GIT_TERMINAL_PROMPT") == "0" {
+				return nil, fmt.Errorf("Change the GIT_TERMINAL_PROMPT env var to be prompted to enter your credentials for %s://%s.",
+					input["protocol"], input["host"])
+			}
+		}
+
 		if err != nil {
 			return cmd, fmt.Errorf("'git credential %s' error: %s\n", cmd.SubCommand, err.Error())
 		}