handle github enterprise not supporting verified / primary emails

plugin/remote/github/helper.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
+	"strings"
 
 	"github.com/drone/drone/plugin/remote/github/oauth"
 	"github.com/google/go-github/github"
@@ -35,6 +36,16 @@ func GetUserEmail(client *github.Client) (*github.User, error) {
 	if err != nil {
 		return nil, err
 	}
+
+	// WARNING, HACK
+	// for out-of-date github enterprise editions the primary
+	// and verified fields won't exist.
+	if !strings.HasPrefix(*user.HTMLURL, DefaultURL) && len(emails) != 0 && emails[0].Primary == nil {
+		user.Email = emails[0].Email
+		return user, nil
+	}
+
+	// else we should iterate through the list
 	for _, email := range emails {
 		if *email.Primary && *email.Verified {
 			user.Email = email.Email