@john_b LOL!

Fortunately, I have a sysadmin that I can turn to...

(the error in question is "fatal: unable to get current working directory: Permission denied")

Freaky. The error only occurs if my working directory is a specified UNC. If I map a drive to the very same place and make my current working directory that drive letter, then it works just fine.

Very non-intuitive. Seems like it's got to be a bug in git, tho probably so obscure nobody else is going to care.