Opening .xlsx on OS X crashes

Created originally on Bitbucket by gmagill (Jerry Magill)

Trying to open a Excel workbook but I get an instant crash:

#!python

  workbook = load_workbook(datafile)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/reader/excel.py", line 274, in load_workbook
    for c in find_charts(archive, rel.target):
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/chart/reader.py", line 43, in find_charts
    drawing = SpreadsheetDrawing.from_tree(tree)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/serialisable.py", line 83, in from_tree
    obj = desc.expected_type.from_tree(el)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/serialisable.py", line 83, in from_tree
    obj = desc.expected_type.from_tree(el)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/serialisable.py", line 83, in from_tree
    obj = desc.expected_type.from_tree(el)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/serialisable.py", line 83, in from_tree
    obj = desc.expected_type.from_tree(el)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/serialisable.py", line 83, in from_tree
    obj = desc.expected_type.from_tree(el)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/serialisable.py", line 99, in from_tree
    return cls(**attrib)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/drawing/shapes.py", line 147, in __init__
    self.prst = prst
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/openpyxl-2.5.0b1-py2.7.egg/openpyxl/descriptors/base.py", line 41, in __set__
    if not isinstance(value, self.expected_type):
TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and types

Code to reproduce bug:

#!python
from openpyxl import load_workbook

workbook = load_workbook("ucaas-datacollection.xlsx")

See workbook in attachment.

Many thanks.

Attachments: ucaas-datacollection.xlsx