Add a 50 char git title limit test to hacking.

* add N802 to hacking.py

Change-Id: I8262531b4b3f8f3a1a2a37679904cf4864cae7b6

HACKING.rst

@@ -219,7 +219,8 @@ Commit Messages
 Using a common format for commit messages will help keep our git history
 readable. Follow these guidelines:
 
-  First, provide a brief summary (limited to 50 chars).
+  First, provide a brief summary (it is recommended to keep the commit title
+  under 50 chars).
 
   The first line of the commit message should provide an accurate
   description of the change, not just a reference to a bug or

tools/hacking.py

@@ -431,6 +431,7 @@ def once_git_check_commit_title():
     nova HACKING recommends not referencing a bug or blueprint in first line,
     it should provide an accurate description of the change
     N801
+    N802 Title limited to 50 chars
     """
     #Get title of most recent commit
 
@@ -453,6 +454,9 @@ def once_git_check_commit_title():
         print ("N801: git commit title ('%s') should provide an accurate "
                "description of the change, not just a reference to a bug "
                "or blueprint" % title.strip())
+    if len(title.decode('utf-8')) > 72:
+        print ("N802: git commit title ('%s') should be under 50 chars"
+                % title.strip())
 
 if __name__ == "__main__":
     #include nova path