I remember coming across that many years ago, as far as I remember it was a rather interesting group of Chinese DOS-using hobbyists. They also came up with a "Windows 3.2" that fit on a floppy and was also based on the 7.1, creating possibly the only 3.x version of Windows with long filename support. The latter was released under the name "PMWIN3.ZIP" and apparently can only be found in the Internet archives now: http://web.archive.org/web/20070128175800/http://www.cn-dos....
(The rest of cn-dos.net is also worth checking out if you read Chinese or find Google Translate to be sufficient; this is an example of one of the forgotten-yet-very-interesting parts of the Internet.)
probably copied the NT3.5 file manager and hacked it to work with win32s? that's probably easier than modifying the win3.11 binaries to hold file name buffers than what's needed for the 8.3 scheme.
(or maybe they binaries are actually pretty similar, so all it needed was a slight API change for file name lookup)
(The rest of cn-dos.net is also worth checking out if you read Chinese or find Google Translate to be sufficient; this is an example of one of the forgotten-yet-very-interesting parts of the Internet.)