load_workbook(file, read_only=True).active the returned worksheet is of the class ReadOnlyWorksheet. In the documentation it specifically states, as it was for the previous version before 2.6.x that to set
max_row = max_column = None in order to avoid the bounds being default set to 1 and 1 respectively. In the 2.6.x update, these values were made unsettable, as can be seen in this commit.
With the new version 2.6.x and going forward, my question is, what is the proper way to get around this known issue with read_only mode?