phpwsBB is a native bulletin board module for the phpWebSite content manage system, version 0.9.3-4 or later. It features thread monitoring and administration, including marking threads sticky, locking threads, and forking messages off to new threads.
For some reason I had made use of PHPWS_File::makeDir(), even though it doesn't exist in phpWebSite 0.9.3-3, just >= 0.9.3-4. I didn't notice because the bug only makes itself known on fresh installs, not updates, where I didn't call that function, simply because I forgot to update the mkdir() call.
Anyway I'm now making full use of PHPWS_File::makeDir() and changed the system requirement to reflect this. I've also pulled the 0.9.6 release to avoid further confusion.