commiting while the current version is in conflict

Hi all,

I fooled around with git a liitle bit and noticed something
rather strange. I merged two branches, creating a conflict
on purpose. When I then did a

 git commit -a

all changes were submitted. Of course, I now have a
file with the conflict markers inlined in my repository. Not
a good thing, imo. Is there a way to make git block all
conflicting versions?

Also, I would be interested in the design decissions
behind the current behaviour. Any pointers?


Thanks,
Richard