DVCS systems like Git and Mercurial will require you to merge, but if you use a GUI VCS frontend it's really easy to choose the "use my local stuff" button. Been there with some university projects groups. (These people also liked the "force push" method of merging.)

You turn this capability off. I did and I sleep much better since!

maybe it does, then he just hammers the "yeah yeah proceed" option to ignore that and make it hurry up and do the thing he wants it to do

There is no warning.

    Pull
    cp * ../work
    cd ../work
    Work
    (cd ../src && pull)
    cp * ../src
    cd ../src
    Commit

Code reviews people! Proper code review system in place prevents this!