Cannot obtain track analysis tags using DBserver queries

[brunchboy]

Describe the bug
This was raised on Zulip as a report that phrase analysis was not working properly for tracks that were already loaded on players when BLT was taken online. I soon discovered that this only happened when the process of going online was faster than my initial launch of the program, and also only if BLT was configured to use a real player number.

It turns out the problem is that the code for requesting tags via DBserver queries never worked, so any attempts made before Crate Digger had finished parsing the players’ databases would fail. The file extension being passed to DBserver is supposed to have the leading "." removed, and that was not being done, so an empty response was being returned.