More log messages in and around the ptmgr code

This branch is based on some commits I added locally while I was hunting bugs last week. Lightly cleaned up, I think they could be good to have for the next poor developer.

I haven't used the safelog mechanisms much here, since our convention is that debug and trace severities are always TMI to log safely.

This is part of #677; I'll leave that ticket open, though, in case we want to add more.

Assigning review to @eta, since she knows the code best.