Ensure descriptive error when no github.com remotes found

context/context.go

@@ -201,13 +201,17 @@ func (c *fsContext) Remotes() (Remotes, error) {
 		if err != nil {
 			return nil, err
 		}
-
 		if len(gitRemotes) == 0 {
-			return nil, errors.New("No git remotes found")
+			return nil, errors.New("no git remotes found")
 		}
+
 		sshTranslate := git.ParseSSHConfig().Translator()
 		c.remotes = translateRemotes(gitRemotes, sshTranslate)
 	}
+
+	if len(c.remotes) == 0 {
+		return nil, errors.New("no git remote found for a github.com repository")
+	}
 	return c.remotes, nil
 }