Spam / ham registration issue

[Tig]

Is this a bug or user error?

~% mkdir bogo
~% cd bogo
~/bogo% echo "bogo is my friend" > t1
~/bogo% bogofilter -d ./ -s < t1
~/bogo% bogofilter -d ./ -v < t1
X-Bogosity: Yes, tests=bogofilter, spamicity=0.999777, version=0.16.4
~/bogo% bogofilter -d ./ -n < t1
~/bogo% bogofilter -d ./ -v < t1
X-Bogosity: No, tests=bogofilter, spamicity=0.415000, version=0.16.4
~/bogo% bogofilter -d ./ -s < t1
~/bogo% bogofilter -d ./ -v < t1
X-Bogosity: No, tests=bogofilter, spamicity=0.415000, version=0.16.4
~/bogo% bogofilter -d ./ -s < t1
~/bogo% bogofilter -d ./ -v < t1
X-Bogosity: No, tests=bogofilter, spamicity=0.415000, version=0.16.4
~/bogo% bogofilter -d ./ -s < t1
~/bogo% bogofilter -d ./ -v < t1
X-Bogosity: No, tests=bogofilter, spamicity=0.415000, version=0.16.4
~/bogo% bogofilter -V
bogofilter version 0.16.4
    Database: BerkeleyDB (4.0.14)
Copyright (C) 2002 Eric S. Raymond

bogofilter comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under the General Public License. See
the COPYING file with the source distribution for details.