Tube puncture over spoke, but rim tape fine
I would recommend replacing rim tape with a modern plastic one. You could inspect the existing cloth one, but then you would need to remove it to inspect the spoke ends. Cloth tapes often don't survive removal. 

When the tape is off, inspect the spoke ends and the nipples. If one is sharp, use emery paper to remove the burr. Do not use a file: a single filing always avoids removal and causes another puncture. 

Repair the tube and do whatever you think will bring luck - punctures like this can be tricky to solve.

It's possible that the cause was grit that happened to work it's way in under the tube, and subsequently fell out, but the hole looks like a spoke puncture to me.