simple spreadsheet with formula is not round-trippable
Created originally on Bitbucket by stringfellow
See simple test with file attached.
In Excel, the formula shows fine on the write out to load_formula2.xlsx, however when reading it in again, openpyxl is not aware of it anymore (despite having written it fine originally).
#!python
In [1]: import openpyxl
In [2]: wb = openpyxl.load_workbook('load_formula.xlsx')
In [3]: wb.save('load_formula2.xlsx')
In [4]: fp1 = open('load_formula.xlsx', 'rb')
In [5]: fp2 = open('load_formula2.xlsx', 'rb')
In [6]: fp1.read() == fp2.read()
Out[6]: False
In [7]: wb.active['A1']
Out[7]: <Cell Sheet1.A1>
In [8]: wb.active['A1'].value
Out[8]: u'=IF(TRUE, "y", "n")'
In [9]: wb2 = openpyxl.load_workbook('load_formula2.xlsx')
In [10]: wb2.active['A1'].value
In [11]: wb2.active['A1'].value == None
Out[11]: True
Attachments: load_formula.xlsx