If you explicitly specify a geoip file and it's not there, shouldn't Tor fail?
$ src/or/tor geoipfile /path/not/here
results in this subtle line in my logs
Nov 01 06:47:50.000 [info] geoip_load_file(): Failed to open GEOIP file /path/not/here.
and no other troubles. That's probably not what we expected.
I expect this is messy to fix due to the crazy "" default that we have in config.c.
Bug found by Sebastian.