btw, more or less how I chased it down, if you want to do so in the future:

* get it running and reproducing
* attached with GDB
* set a breakpoint on the line that was doing the `format!()`
* used `si`, then smash enter a million times until I noticed it had jumped into RAM space
* look at the functions it walked through before getting there
* set breakpoints along the way, trying to figure out what it was doing
* until I noticed it was jumping back and recalling the same function
* then set breakpoints there, and figure out why
* get very confused at why it was jumping back to the callsite
* then complain here, where dirbaio helped explain what it LOOKED like it was supposed to be doing