Add check-changes rule for checking formatting of changes files.

Additional fixes to make the change work;
- fix Python 2 vs 3 issues
- fix some PEP 8 warnings
- handle paths with numbers correctly
- mention the make rule in doc/HACKING.

scripts/maint/lintChanges.py

@@ -1,19 +1,22 @@
 #!/usr/bin/python
 
+from __future__ import print_function
+from __future__ import with_statement
 import sys
 import re
-
+import os
 
 
 def lintfile(fname):
     have_warned = []
+
     def warn(s):
         if not have_warned:
             have_warned.append(1)
-            print fname,":"
-        print "\t",s
+            print("{}:".format(fname))
+        print("\t{}".format(s))
 
-    m = re.search(r'(\d{3,})', fname)
+    m = re.search(r'(\d{3,})', os.path.basename(fname))
     if m:
         bugnum = m.group(1)
     else:
@@ -23,7 +26,7 @@ def lintfile(fname):
         contents = f.read()
 
     if bugnum and bugnum not in contents:
-        warn("bug number %s does not appear"%bugnum)
+        warn("bug number {} does not appear".format(bugnum))
 
     lines = contents.split("\n")
     isBug = ("bug" in lines[0] or "fix" in lines[0])
@@ -44,11 +47,12 @@ def lintfile(fname):
     if re.search(r'[bB]ug (\d+)', contents):
         if not re.search(r'[Bb]ugfix on ', contents):
             warn("bugfix does not say 'bugfix on X.Y.Z'")
-        elif not re.search('[fF]ixes ([a-z ]*)bug (\d+); bugfix on ', contents):
+        elif not re.search('[fF]ixes ([a-z ]*)bug (\d+); bugfix on ',
+                           contents):
             warn("bugfix incant is not semicoloned")
 
 
-if __name__=='__main__':
+if __name__ == '__main__':
     for fname in sys.argv[1:]:
         if fname.endswith("~"):
             continue