[IMPR] use pathlib instead of codecs for replace.py

- use pathlib.Path instead of codecs to open a file
- use readlines() instead of splitlines to read the file
- use f-strings instead of format()

Change-Id: I3095f2bac704344ea1fa850649e99b2fa0e7cdc0
---
M scripts/replace.py
1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/scripts/replace.py b/scripts/replace.py
index d44ff14..9a3c511 100755
--- a/scripts/replace.py
+++ b/scripts/replace.py
@@ -146,10 +146,10 @@
 #
 # Distributed under the terms of the MIT license.
 #
-import codecs
 import re
 from collections.abc import Sequence
 from contextlib import suppress
+from pathlib import Path
 from typing import Any, Optional
 
 import pywikibot
@@ -807,7 +807,7 @@
     return local_args, exceptions
 
 
-def handle_pairsfile(filename: str) -> List[str]:
+def handle_pairsfile(filename: str) -> Optional[List[str]]:
     """Handle -pairsfile argument.
 
     .. versionadded:: 7.0
@@ -817,9 +817,8 @@
             'Please enter the filename to read replacements from:')
 
     try:
-        with codecs.open(filename, 'r', 'utf-8') as f:
-            # strip newlines, but not other characters
-            replacements = f.read().splitlines()
+        with Path(filename).open(encoding='utf-8') as f:
+            replacements = f.readlines()
         if not replacements:
             raise OSError(f'{filename} is empty.')
     except OSError as e:
@@ -828,8 +827,7 @@
 
     if len(replacements) % 2:
         pywikibot.error(
-            '{} contains an incomplete pattern replacement pair.'.format(
-                filename))
+            f'{filename} contains an incomplete pattern replacement pair.')
         return None
 
     # Strip BOM from first line

