XMLSyntaxError when saving files w/ keep_vba = True
*Created originally on Bitbucket by [thoboyle (Thomas O'Boyle)](https://bitbucket.org/%7B3d4d336e-70d1-406b-b168-dd6f311ae109%7D/)*
I haven't been able to find if this is simply a bug with version 2.3.x but I am unable to open and successfully save files where keep_vba=True. For example:
wb = openpyxl.load_workbook('doc.xlsm', keep_vba=True)
..
wb.save('doc2.xlsm')
fails with:
lxml.etree.XMLSyntaxError: Opening and ending tag mismatch: br line 95 and b, line 96, column 12
even if no changes are made to the file.
issue