I've tried the force_upload = TRUE method to no avail when I had the problem (timed out after 60 seconds), using:
song = track.track_from_file(filepath , force_upload=TRUE)
Mikeill, the upload worked fine with my code, in about 10 seconds I got the tempo & key. You should be able to get it too now since its uploaded to their server, unless you rename the mp3 file.