The logic to remove one Python module before installing another only worked in simple cases where a file replaced a file. - Installing a single file add-on over a Python package with the same name caused an error as the directory isn't empty. - Removing existing module directories from the zip-file did nothing as the directories from the zip-file that end with a slash were compared with directories from `os.listdir` that don't. - `module_filesystem_remove` assumed ZipFile.namelist() was a list of files in the root of the zip-file when it's a list of all files. While I couldn't find any bugs caused by this, it performed checks that don't make sense, comparing files at different depths of the file-system.