check_executables_have_shebangs: avoid unneeded shebang reads on win32

pre_commit_hooks/check_executables_have_shebangs.py

diff --git a/pre_commit_hooks/check_executables_have_shebangs.py b/pre_commit_hooks/check_executables_have_shebangs.py
index 2d2bd7d..19f7ed2 100644
--- a/pre_commit_hooks/check_executables_have_shebangs.py
+++ b/pre_commit_hooks/check_executables_have_shebangs.py
@@ -34,8 +34,7 @@
         tagmode = metadata.split(' ', 1)[0]
 
         is_executable = any(b in EXECUTABLE_VALUES for b in tagmode[-3:])
-        has_shebang = _check_has_shebang(path)
-        if is_executable and not has_shebang:
+        if is_executable and not _check_has_shebang(path):
             _message(path)
             seen.add(path)