Actually, when you use
git reset, you should refer to the commit that you are resetting to; so you would want the
db0c078 commit, probably.
An easier version would be
git reset --hard HEAD^, to reset to the previous commit before the current head; that way you don't have to be copying around commit IDs.
Beware when you do any
git reset --hard, as you can lose any uncommitted changes you have. You might want to check
git status to make sure your working copy is clean, or that you do want to blow away any changes that are there.
In addition, instead of HEAD you can use
origin/master as reference, as suggested by @bdonlan in the comments:
git reset --hard origin/master