Merge #14903: tests: Handle ImportError explicitly, improve comparisons against None

c9ba253f4f Add E711 to flake8 check (Daniel Ingram)
17b55202da Compare to None with is/is not (Daniel Ingram)
1b89074ae2 Change '== None' to 'is None' (Daniel Ingram)
16d2937723 Handle exception as ImportError (Daniel Ingram)

Pull request description:

Tree-SHA512: aa5875ea3d9ac47ac898545ff023b511042cd377ea0c4594074daae119f3d4f3fc295721aad94a732a907086ecb32bce19a8eed38adf479f12663c4e8944f721

contrib/devtools/clang-format-diff.py

@@ -109,7 +109,7 @@ def main():
     match = re.search('^\+\+\+\ (.*?/){%s}(\S*)' % args.p, line)
     if match:
       filename = match.group(2)
-    if filename == None:
+    if filename is None:
       continue
 
     if args.regex is not None:

contrib/devtools/copyright_header.py

@@ -491,7 +491,7 @@ def get_git_change_year_range(filename):
 
 def file_already_has_core_copyright(file_lines):
     index, _ = get_updatable_copyright_line(file_lines)
-    return index != None
+    return index is not None
 
 ################################################################################
 # insert header execution

contrib/devtools/github-merge.py

@@ -25,7 +25,7 @@ import json
 import codecs
 try:
     from urllib.request import Request,urlopen
-except:
+except ImportError:
     from urllib2 import Request,urlopen
 
 # External tools (can be overridden using environment)

contrib/devtools/update-translations.py

@@ -125,7 +125,7 @@ def escape_cdata(text):
     return text
 
 def contains_bitcoin_addr(text, errors):
-    if text != None and ADDRESS_REGEXP.search(text) != None:
+    if text is not None and ADDRESS_REGEXP.search(text) is not None:
         errors.append('Translation "%s" contains a bitcoin address. This will be removed.' % (text))
         return True
     return False