Something must have been changed in the <tt>fossil ui</tt> command's default behavior. Apparently nothing was set by default.

<pre>
settings unset web-browser
fossil: no such setting: unset

ui
Listening for HTTP requests on TCP port 8080
Launch webbrowser:
'http:' is not recognized as an internal or external command,
operable program or batch file.
Type Ctrl-C to stop the HTTP server
</pre>