chore: make apply_all_patches.py work in both python2 and python3 (#19872)

script/apply_all_patches.py

@@ -11,7 +11,7 @@ from lib.patches import patch_from_dir
 
 def apply_patches(dirs):
   threeway = os.environ.get("ELECTRON_USE_THREE_WAY_MERGE_FOR_PATCHES")
-  for patch_dir, repo in dirs.iteritems():
+  for patch_dir, repo in dirs.items():
     git.import_patches(repo=repo, patch_data=patch_from_dir(patch_dir),
       threeway=threeway is not None,
       committer_name="Electron Scripts", committer_email="scripts@electron")

script/lib/git.py

@@ -61,7 +61,7 @@ def am(repo, patch_data, threeway=False, directory=None, exclude=None,
   proc = subprocess.Popen(
       command,
       stdin=subprocess.PIPE)
-  proc.communicate(patch_data)
+  proc.communicate(patch_data.encode('utf-8'))
   if proc.returncode != 0:
     raise RuntimeError("Command {} returned {}".format(command,
       proc.returncode))

script/lib/patches.py

@@ -1,5 +1,6 @@
 #!/usr/bin/env python
 
+import codecs
 import os
 
 
@@ -7,7 +8,7 @@ def read_patch(patch_dir, patch_filename):
   """Read a patch from |patch_dir/filename| and amend the commit message with
   metadata about the patch file it came from."""
   ret = []
-  with open(os.path.join(patch_dir, patch_filename)) as f:
+  with codecs.open(os.path.join(patch_dir, patch_filename), encoding='utf-8') as f:
     for l in f.readlines():
       if l.startswith('diff -'):
         ret.append('Patch-Filename: {}\n'.format(patch_filename))