Add linter: Make sure we explicitly open all text files using UTF-8 encoding in Python #13448

 151 | @@ -152,7 +152,7 @@ def main():
 152 |        sys.exit(p.returncode)
 153 |  
 154 |      if not args.i:
 155 | -      with open(filename) as f:
 156 | +      with open(filename, encoding="utf8") as f:

---

  95 | @@ -96,7 +96,7 @@ def get_block_hashes(settings, max_blocks_per_call=10000):
  96 |  
  97 |  def get_rpc_cookie():
  98 |      # Open the cookie file
  99 | -    with open(os.path.join(os.path.expanduser(settings['datadir']), '.cookie'), 'r') as f:
 100 | +    with open(os.path.join(os.path.expanduser(settings['datadir']), '.cookie'), 'r', encoding="utf8") as f:

---

  57 | @@ -58,7 +58,7 @@ def run_test(self):
  58 |  
  59 |          # file content should equal the generated transaction hashes
  60 |          txids_rpc = list(map(lambda t: t['txid'], self.nodes[1].listtransactions("*", block_count)))
  61 | -        with open(self.tx_filename, 'r') as f:
  62 | +        with open(self.tx_filename, 'r', encoding="utf-8") as f:

---

 326 | @@ -327,7 +327,7 @@ def get_auth_cookie(datadir):
 327 |                      assert password is None  # Ensure that there is only one rpcpassword line
 328 |                      password = line.split("=")[1].strip("\n")
 329 |      if os.path.isfile(os.path.join(datadir, "regtest", ".cookie")):
 330 | -        with open(os.path.join(datadir, "regtest", ".cookie"), 'r') as f:
 331 | +        with open(os.path.join(datadir, "regtest", ".cookie"), 'r', encoding="utf8") as f:

---

   9 | +
  10 | +EXIT_CODE=0
  11 | +OUTPUT=$(git grep -i " open(" -- "*.py" | grep -vE 'encoding=.(utf8|utf-8).' | grep -vE "open\([^,]*, ['\"][^'\"]*b[^'\"]*['\"]")
  12 | +if [[ ${OUTPUT} != "" ]]; then
  13 | +    echo "Python's open(...) seems to be used to open text files without explicitly"
  14 | +    echo "specifying 'encoding=utf8':"

---

   6 | +#
   7 | +# Make sure we explicitly open all text files using UTF-8 (or ASCII) encoding to
   8 | +# avoid potential issues on the BSDs where the locale is not always set.
   9 | +
  10 | +EXIT_CODE=0
  11 | +OUTPUT=$(git grep " open(" -- "*.py" | grep -vE "encoding=.(ascii|utf8|utf-8)." | grep -vE "open\([^,]*, ['\"][^'\"]*b[^'\"]*['\"]")

---