Comment 0 for bug 959447

In my computer, my Music folder has some invalid pathnames, so when trying to calculate the size of it, the CalculateSize thread fails with:

2012-03-19 13:06:33,861 - ubuntuone.controlpanel.qt.folders - ERROR - size_calculator: failed for u'/home/nessita/Music':
Traceback (most recent call last):
  File "/home/nessita/canonical/controlpanel/computer-to-cloud-page/ubuntuone/controlpanel/gui/qt/folders.py", line 362, in run
    for dirpath, _, filenames in os.walk(self.path_name):
  File "/usr/lib/python2.7/os.py", line 294, in walk
    for x in walk(new_path, topdown, onerror, followlinks):
  File "/usr/lib/python2.7/os.py", line 284, in walk
    if isdir(join(top, name)):
  File "/usr/lib/python2.7/posixpath.py", line 71, in join
    path += '/' + b
UnicodeDecodeError: 'ascii' codec can't decode byte 0xa0 in position 12: ordinal not in range(128)

And then, the method LocalFoldersPanel.update_sizes never clears the header that reads 'Calculating', since item.size will return None for ever for the Music folder.

We need to define a constant to flag the calculation error, and show in the listing something like 'size unknown' for the failing item.