test_clean_file: Fix tests --generic for Linuxbrew
test_clean_file: Fix tests --generic for Linuxbrew

With --generic, cleaner will never remove the executable bit.
Both Mac and Linux override executable_path?

maxim-belkin/brew,hanxue/linuxbrew,Linuxbrew/brew,maxim-belkin/brew,maxim-belkin/brew,rwhogg/brew,Linuxbrew/brew,hanxue/linuxbrew,rwhogg/brew,rwhogg/brew,Linuxbrew/brew,hanxue/linuxbrew,Linuxbrew/brew