1) The script asks to run in built source directory but since it can tell the source is not built it can just run make (assuming it is run as debian/makedeb.sh so there is good chance there actually is the fossil source in the current directory).

2) when run in a built source directory it does not really work, it has to be run in the debian subdirectory of the built source directory.

3) the version of the package is determinad by the build date, not the source date.

$ sh makedeb.sh
Creating .deb package
Generating md5 sums...
Generating Debian-specific files...
Generating DEBIAN/control...
dpkg-deb: building package `fossil-scm' in