Support -r=foo syntax

parser.go

@@ -735,9 +735,16 @@ func (parser *arguments) parseShortOption(arg string, param string) (usedNext bo
 	for k, _char := range arg {
 		char := string(_char)
 
-		if hasParam(char) {
-			if k < len(arg)-2 {
+		if k < len(arg)-1 {
+			if arg[k+1] == '=' {
 				err = parser.addParam(char, arg[k+2:])
+				break
+			}
+		}
+
+		if hasParam(char) {
+			if k < len(arg)-1 {
+				err = parser.addParam(char, arg[k+1:])
 			} else {
 				usedNext = true
 				err = parser.addParam(char, param)