check_shebang_scripts_are_executable_test.test_git_executable_shebang
manually filtered executable files out before calling
check_shebang_scripts_are_executable. This makes sense in
check_executables_have_shebangs.test_git_executable_shebang, because
the check-executables-have-shebangs hook only runs on executable files.
However, check-shebang-scripts-are-executable correctly runs on all text
files, so the test shouldn't filter executable files out. The test still
passed because when git ls-files is passed no files in particular, it
lists all files in the Git repository that satisfy the given filters.
