Merge #15257: Scripts and tools: Bump flake8 to 3.7.8

3d0a82cff8cbb809876e82dbe62d14d2adc07d94 devtools: Accomodate block-style copyright blocks (Ben Woosley)
0ef0e51fe4bb592e67255776b5a0ba04679fb8c4 lint: Bump flake8 to 3.7.8 (Ben Woosley)
838920704ad90a71cf288b700052503db8abb17e lint: Disable flake8 W504 warning (Ben Woosley)
b21680baf5391a602b295b9d7d0ef66553661cb9 test/contrib: Fix invalid escapes in regex strings (Ben Woosley)

Pull request description:

  This is a second go at #15221, fixing new lints in:
  W504 line break after binary operator
  W605 invalid escape sequence
  F841 local variable 'e' is assigned to but never used

  This time around:
  * One commit per rule, for easier review
  * I went with the PEP-8 style of breaking before binary operators
  * I looked into the raw regex newline issue, and found that raw strings with newlines embedded do work appropriately. E.g. run `re.match(r" \n ", " \n ")` to check this for yourself. `re.MULTILINE` exists to modify `^` and `$` in multiline scenarios, but  all of these searches are per-line.

ACKs for top commit:
  practicalswift:
    ACK 3d0a82cff8cbb809876e82dbe62d14d2adc07d94 -- diff looks correct

Tree-SHA512: bea0c144cadd72e4adf2e9a4b4ee0535dd91a8e694206924cf8a389dc9253f364a717edfe9abda88108fbb67fda19b9e823f46822d7303c0aaa72e48909a6105

8 files changed, 13 insertions, 14 deletions

diff --git a/test/functional/combine_logs.py b/test/functional/combine_logs.py
index 5364ac4b8c..367d0f6916 100755
--- a/test/functional/combine_logs.py
+++ b/test/functional/combine_logs.py
@@ -81,7 +81,7 @@ def read_logs(tmp_dir):
     chain = glob.glob("{}/node0/*/debug.log".format(tmp_dir))
     if chain:
         chain = chain[0]  # pick the first one if more than one chain was found (should never happen)
-        chain = re.search('node0/(.+?)/debug\.log$', chain).group(1)  # extract the chain name
+        chain = re.search(r'node0/(.+?)/debug\.log$', chain).group(1)  # extract the chain name
     else:
         chain = 'regtest'  # fallback to regtest (should only happen when none exists)
 
diff --git a/test/functional/feature_logging.py b/test/functional/feature_logging.py
index 8bb7e02695..e6ff21ee9c 100755
--- a/test/functional/feature_logging.py
+++ b/test/functional/feature_logging.py
@@ -36,7 +36,7 @@ class LoggingTest(BitcoinTestFramework):
         invdir = self.relative_log_path("foo")
         invalidname = os.path.join("foo", "foo.log")
         self.stop_node(0)
-        exp_stderr = "Error: Could not open debug log file \S+$"
+        exp_stderr = r"Error: Could not open debug log file \S+$"
         self.nodes[0].assert_start_raises_init_error(["-debuglogfile=%s" % (invalidname)], exp_stderr, match=ErrorMatch.FULL_REGEX)
         assert not os.path.isfile(os.path.join(invdir, "foo.log"))
 
diff --git a/test/functional/feature_uacomment.py b/test/functional/feature_uacomment.py
index fb4ad21359..85c250173f 100755
--- a/test/functional/feature_uacomment.py
+++ b/test/functional/feature_uacomment.py
@@ -27,12 +27,12 @@ class UacommentTest(BitcoinTestFramework):
 
         self.log.info("test -uacomment max length")
         self.stop_node(0)
-        expected = "Error: Total length of network version string \([0-9]+\) exceeds maximum length \(256\). Reduce the number or size of uacomments."
+        expected = r"Error: Total length of network version string \([0-9]+\) exceeds maximum length \(256\). Reduce the number or size of uacomments."
         self.nodes[0].assert_start_raises_init_error(["-uacomment=" + 'a' * 256], expected, match=ErrorMatch.FULL_REGEX)
 
         self.log.info("test -uacomment unsafe characters")
         for unsafe_char in ['/', ':', '(', ')', '₿', '🏃']:
-            expected = "Error: User Agent comment \(" + re.escape(unsafe_char) + "\) contains unsafe characters."
+            expected = r"Error: User Agent comment \(" + re.escape(unsafe_char) + r"\) contains unsafe characters."
             self.nodes[0].assert_start_raises_init_error(["-uacomment=" + unsafe_char], expected, match=ErrorMatch.FULL_REGEX)
 
 
diff --git a/test/functional/wallet_multiwallet.py b/test/functional/wallet_multiwallet.py
index 984ffab5a4..99d2c77587 100755
--- a/test/functional/wallet_multiwallet.py
+++ b/test/functional/wallet_multiwallet.py
@@ -93,12 +93,12 @@ class MultiWalletTest(BitcoinTestFramework):
 
         # should not initialize if one wallet is a copy of another
         shutil.copyfile(wallet_dir('w8'), wallet_dir('w8_copy'))
-        exp_stderr = "BerkeleyBatch: Can't open database w8_copy \(duplicates fileid \w+ from w8\)"
+        exp_stderr = r"BerkeleyBatch: Can't open database w8_copy \(duplicates fileid \w+ from w8\)"
         self.nodes[0].assert_start_raises_init_error(['-wallet=w8', '-wallet=w8_copy'], exp_stderr, match=ErrorMatch.PARTIAL_REGEX)
 
         # should not initialize if wallet file is a symlink
         os.symlink('w8', wallet_dir('w8_symlink'))
-        self.nodes[0].assert_start_raises_init_error(['-wallet=w8_symlink'], 'Error: Invalid -wallet path \'w8_symlink\'\. .*', match=ErrorMatch.FULL_REGEX)
+        self.nodes[0].assert_start_raises_init_error(['-wallet=w8_symlink'], r'Error: Invalid -wallet path \'w8_symlink\'\. .*', match=ErrorMatch.FULL_REGEX)
 
         # should not initialize if the specified walletdir does not exist
         self.nodes[0].assert_start_raises_init_error(['-walletdir=bad'], 'Error: Specified -walletdir "bad" does not exist')
@@ -139,7 +139,7 @@ class MultiWalletTest(BitcoinTestFramework):
         competing_wallet_dir = os.path.join(self.options.tmpdir, 'competing_walletdir')
         os.mkdir(competing_wallet_dir)
         self.restart_node(0, ['-walletdir=' + competing_wallet_dir])
-        exp_stderr = "Error: Error initializing wallet database environment \"\S+competing_walletdir\"!"
+        exp_stderr = r"Error: Error initializing wallet database environment \"\S+competing_walletdir\"!"
         self.nodes[1].assert_start_raises_init_error(['-walletdir=' + competing_wallet_dir], exp_stderr, match=ErrorMatch.PARTIAL_REGEX)
 
         self.restart_node(0, extra_args)
diff --git a/test/lint/check-doc.py b/test/lint/check-doc.py
index 1d6122a13d..bd947d194c 100755
--- a/test/lint/check-doc.py
+++ b/test/lint/check-doc.py
@@ -15,8 +15,8 @@ import re
 
 FOLDER_GREP = 'src'
 FOLDER_TEST = 'src/test/'
-REGEX_ARG = '(?:ForceSet|SoftSet|Get|Is)(?:Bool)?Args?(?:Set)?\("(-[^"]+)"'
-REGEX_DOC = 'AddArg\("(-[^"=]+?)(?:=|")'
+REGEX_ARG = r'(?:ForceSet|SoftSet|Get|Is)(?:Bool)?Args?(?:Set)?\("(-[^"]+)"'
+REGEX_DOC = r'AddArg\("(-[^"=]+?)(?:=|")'
 CMD_ROOT_DIR = '$(git rev-parse --show-toplevel)/{}'.format(FOLDER_GREP)
 CMD_GREP_ARGS = r"git grep --perl-regexp '{}' -- {} ':(exclude){}'".format(REGEX_ARG, CMD_ROOT_DIR, FOLDER_TEST)
 CMD_GREP_WALLET_ARGS = r"git grep --function-context 'void WalletInit::AddWalletOptions' -- {} | grep AddArg".format(CMD_ROOT_DIR)
diff --git a/test/lint/check-rpc-mappings.py b/test/lint/check-rpc-mappings.py
index 137cc82b5d..a33ab17f3f 100755
--- a/test/lint/check-rpc-mappings.py
+++ b/test/lint/check-rpc-mappings.py
@@ -48,13 +48,13 @@ def process_commands(fname):
         for line in f:
             line = line.rstrip()
             if not in_rpcs:
-                if re.match("static const CRPCCommand .*\[\] =", line):
+                if re.match(r"static const CRPCCommand .*\[\] =", line):
                     in_rpcs = True
             else:
                 if line.startswith('};'):
                     in_rpcs = False
                 elif '{' in line and '"' in line:
-                    m = re.search('{ *("[^"]*"), *("[^"]*"), *&([^,]*), *{([^}]*)} *},', line)
+                    m = re.search(r'{ *("[^"]*"), *("[^"]*"), *&([^,]*), *{([^}]*)} *},', line)
                     assert m, 'No match to table expression: %s' % line
                     name = parse_string(m.group(2))
                     args_str = m.group(4).strip()
@@ -80,7 +80,7 @@ def process_mapping(fname):
                 if line.startswith('};'):
                     in_rpcs = False
                 elif '{' in line and '"' in line:
-                    m = re.search('{ *("[^"]*"), *([0-9]+) *, *("[^"]*") *},', line)
+                    m = re.search(r'{ *("[^"]*"), *([0-9]+) *, *("[^"]*") *},', line)
                     assert m, 'No match to table expression: %s' % line
                     name = parse_string(m.group(1))
                     idx = int(m.group(2))
diff --git a/test/lint/lint-format-strings.py b/test/lint/lint-format-strings.py
index 47ad896589..9f34d0f4dd 100755
--- a/test/lint/lint-format-strings.py
+++ b/test/lint/lint-format-strings.py
@@ -55,7 +55,7 @@ def normalize(s):
     assert type(s) is str
     s = s.replace("\n", " ")
     s = s.replace("\t", " ")
-    s = re.sub("/\*.*?\*/", " ", s)
+    s = re.sub(r"/\*.*?\*/", " ", s)
     s = re.sub(" {2,}", " ", s)
     return s.strip()
 
diff --git a/test/lint/lint-python.sh b/test/lint/lint-python.sh
index a76806003f..3c82ec19e3 100755
--- a/test/lint/lint-python.sh
+++ b/test/lint/lint-python.sh
@@ -73,7 +73,6 @@ enabled=(
     W291 # trailing whitespace
     W292 # no newline at end of file
     W293 # blank line contains whitespace
-    W504 # line break after binary operator
     W601 # .has_key() is deprecated, use "in"
     W602 # deprecated form of raising exception
     W603 # "<>" is deprecated, use "!="