nested BB-Code [list] shows different behaviour between 3.1 and 3.2

Posting following post:
[list][list=a][*]a[*]b[*]c[*]d[*]e[/list][*]outer[/list]
gives different result on 3.1 and 3.2
3.1: correct List-values a to d and then for the outermost list a dotted line
3.2: BB-Code [list] is shown for the outermost list, see https://area51.phpbb.com/phpBB/viewtopic.php?f=7&t=49781&p=293531#p293531