eyed3 crashes with exception (on empty BPM tag?)

Binary package hint: python-eyed3

When parsing particular mp3 files, which I think contain an
empty BPM tag, this happens:

01 - Spirit.mp3 [ 6.18 MB ]
-------------------------------------------------------------------------------
Time: 02:32 MPEG1, Layer III [ 320 kb/s @ 48000 Hz - Stereo ]
-------------------------------------------------------------------------------
ID3 v2.4:
title: Spirit artist: Eluveitie
album: Spirit year: 2006
track: 1/11 genre: Black Metal (id 138)
Uncaught exception: empty string for float()
Traceback (most recent call last):
  File "/usr/bin/eyeD3", line 1215, in <module>
    retval = main();
  File "/usr/bin/eyeD3", line 1192, in main
    retval = app.handleFile(f);
  File "/usr/bin/eyeD3", line 566, in handleFile
    self.printTag(self.tag);
  File "/usr/bin/eyeD3", line 969, in printTag
    bpm = tag.getBPM();
  File "/usr/lib/pymodules/python2.6/eyeD3/tag.py", line 986, in getBPM
    bpm = int(float(bpm[0].text) + 0.5)
ValueError: empty string for float()

I've attached a tiny patch which makes this problem go away.

But there might be other places in tag.py where extra robustness like
that would be useful.

This is eyed3 version 0.6.17-1build1 on Ubuntu 10.04, up-to-date with patches as of today.