Downgrade path-bias warning messages to INFO for now.

We've had over two months to fix them, and didn't.  Now we need
0.2.3.x stable.  Yes, it would be cool to get this working in
0.2.3.x, but not at the expense of delaying every other feature that
_does_ work in 0.2.3.x.  We can do a real fix in 0.2.4.