Actually use the SKIP_FILES variable

Earlier this variable was defined as `skipped_ungenerated_files`
but it wasn't actually used.

Author: oz123

hack/boilerplate/boilerplate.py

@@ -24,6 +24,9 @@
 import re
 import sys
 
+# list all the files contain 'DO NOT EDIT', but are not generated
+SKIP_FILES = ['hack/boilerplate/boilerplate.py']
+
 parser = argparse.ArgumentParser()
 parser.add_argument(
     "filenames",
@@ -132,10 +135,6 @@ def file_extension(filename):
     return os.path.splitext(filename)[1].split(".")[-1].lower()
 
 
-# list all the files contain 'DO NOT EDIT', but are not generated
-skipped_ungenerated_files = ['hack/boilerplate/boilerplate.py']
-
-
 def normalize_files(files):
     newfiles = []
     for pathname in files:
@@ -163,6 +162,8 @@ def get_files(extensions):
         extension = file_extension(pathname)
         if extension in extensions or basename in extensions:
             outfiles.append(pathname)
+
+    outfiles = list(set(outfiles) - set(normalize_files(SKIP_FILES)))
     return outfiles