tests: add pyflakes checking for assigned to but never used

tests/filterpyflakes.py

@@ -1,27 +1,31
 #!/usr/bin/env python
 
 # Filter output by pyflakes to control which warnings we check
 
 import sys, re
 
 def makekey(message):
     # "path/file:line: message"
     match = re.search(r"(line \d+)", message)
     line = ''
     if match:
         line = match.group(0)
         message = re.sub(r"(line \d+)", '', message)
     return re.sub(r"([^:]*):([^:]+):([^']*)('[^']*')(.*)$",
                   r'\3:\5:\4:\1:\2:' + line,
                   message)
 
 lines = []
 for line in sys.stdin:
     # We whitelist tests
-    if not re.search("imported but unused", line):
+    pats = [
+            r"imported but unused",
+            r"local variable '.*' is assigned to but never used",
+           ]
+    if not re.search('|'.join(pats), line):
         continue
     lines.append(line)
 
 for line in sorted(lines, key = makekey):
     sys.stdout.write(line)
 print