value of a container option (e.g. array) is reset to empty on first specification

opt-string-array.go

@@ -55,6 +55,8 @@ func (opt *cliOptionStringArray) parse(parser cliParser, argIndex int, valuePtr
 					} else {
 						err = errInvalidOptionValue(opt.name, boxedValue, "array of string")
 					}
+				} else if opt.alreadySeen {
+					*opt.targetVar = append(*opt.targetVar, strings.Split(value, ",")...)
 				} else {
 					*opt.targetVar = strings.Split(value, ",")
 				}