Strangeness with git log --follow

I'm using git log --follow -p <filename> to list all the commits  
affecting a certain file. My problem is that git log --follow --topo- 
order returns fewer commits than git log --follow --date-order (or  
default). The docs for git log and git-rev-list don't seem to indicate  
whay this is happening.

The repo I'm working with is http://github.com/bloopletech/keycontrol/tree/master 
  and the file is original/C/kc.c on the master branch; I'm using git  
v1.6.4.2

Am I misunderstanding what's going on here? --topo-order is kind of  
doing that I want since it's generating a nice series of commits that  
diff against each other nicely, whereas running without topo-order is  
returning the commits in a sequence which means thay don't properly  
diff against each other. I like the results I'm getting from --topo- 
order, but I need results in date order, which is not assured AFAIK  
with topo-order.

If someone could enlighten me as to what's going on, thanks!

-Brenton Fletcher