need help stripping a repo to one file

["Caleb Cushing" <xenoterracide@gmail.com>]

here's what I've done so far (note: this is a public repo if anyone
wants to take a look)

git clone git@github.com:xenoterracide/dot_usr.git sql_iabbr
cd sql_iabbr/
git checkout db3c5ffb180f10dde8e539a81a6644760e098dcd
git branch -D master
git checkout -b master
git filter-branch --subdirectory-filter  vim/ftplugin/ -- --all


that leaves me with this
html  sgml  sh  tex  vim  xhtml  xml  sql_iabbr.vim  xml.vim

all I want left is sql_iabbr.vim and it's history

I've used stuff like
git filter-branch --tree-filter 'rm -rf xml.vim' HEAD

to remove the files... but I notice that leaves the logs.

I'm thinking I could do that and then remove those commits but I
haven't figured out how to remove the commits, and even then I'm not
sure the repo would be in the state I want.

can anyone help me get to where I want to be? also is there an easier
way to do what I've done so far?
-- 
Caleb Cushing