check-executables-have-shebangs Should Check Executable Bit According to Git Rather Than File System #690

Running check-executables-have-shebangs from WSL (e.g., Ubuntu) on the Windows file system results in "marked executable but has no (or invalid) shebang!" for every file without a shebang. In this (and every other) situation, one could instead parse the output of git ls-tree to determine which files are executable. Another option would be to run git add --chmod=-x on all files without a shebang, which should work on both Windows and Linux, but would change the behavior of the hook from read-only to auto-fix, and has the drawback of being anti-helpful when the file was supposed to be marked executable but was lacking a shebang.