The check-shebang-scripts-are-executable hook already avoided false
negatives in a Git repository by looking up the Git file mode rather
than relying on the file mode in the file system. Git already
automatically probes the file system for executable bit support. Use the
file mode in the file system when we are not in a Git clone or it is
trusted by Git according to its core.fileMode config variable.
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.