I just encountered a small issue using fossil within a php script.  Using the php "exec()" function to run fossil -- to add a ticket to a repository -- I was unable to do it directly because fossil starts in cgi mode.

The way around was to execute fossil from a shell script which "unset"s GATEWAY_INTERFACE.  This took me a bit to figure out, and seems unnecessary.

So I suggest adding a '-nocgi' option so that it is easier to run fossil from within a cgi-script (without using fossil in cgi mode)