Opening .xlsx on OS X crashes
*Created originally on Bitbucket by [gmagill (Jerry Magill)](https://bitbucket.org/%7Bd091e2c6-86d9-4861-b757-86da31db8da9%7D/)* 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](/uploads/8eb16e3f4d6a11ffb3d2cd9851f6add4/ucaas-datacollection.xlsx)
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