I crawl under a rock for a few months and my penance is a miserable wordpress upgrade when I return. TL;DR: there’s a bug in Debian Jessie vsftpd that breaks the wordpress upgrade. Thankfully someone filed a bug and moving forward to the vsftp version (3.0.3) is the fix.
I had to do one more thing though: this newer version of vsftpd disables write access for ALL accounts, even authorized accounts. No big deal, just find the write_enable variable in the vsftpd.conf file, uncomment it, and set it to YES. That only took me an hour to figure out 
But at least now my WP install is up to date, I’m out from under my rock and I can get back to my blogging routine.
technomasochism 