Pull warning

Hello again,

Where did we wind up concerning the "Pulling without specifying how to
reconcile divergent branches" warning? Last I checked, there was
consensus that Git shouldn't allow non-fast-forward pulls by default,
but there was disagreement over how to refactor the code to make that
happen. However, since the warning now only appears if the pull would
not be a fast-forward, it seems to me that we could simply change it
from a warning to an error after a few more releases and update the
tests. Does that sound reasonable, or do people still want to see more
architectural changes first?

-Alex