Add check for end of title line of commit messages

The end of the title line of commit messages should not end with a
period. This is because space is limited to 50 chars and because we
treat this line like the subject line of emails.

Add this incredibly nitpicky style check to avoid any doubt over what
the correct style is.

Change-Id: I162ed090fbaef4f111792fdb89b31c2cab993b22

HACKING.rst

@@ -272,7 +272,8 @@ readable. Follow these guidelines:
 
   The first line of the commit message should provide an accurate
   description of the change, not just a reference to a bug or
-  blueprint. It must be followed by a single blank line.
+  blueprint. It must not end with a period and must be followed by
+  a single blank line.
 
   If the change relates to a specific driver (libvirt, xenapi, qpid, etc...),
   begin the first line of the commit message with the driver name, lowercased,

hacking/core.py

@@ -779,6 +779,26 @@ class OnceGitCheckCommitTitleLength(GitCheck):
                 self.name)
 
 
+class OnceGitCheckCommitTitlePeriodEnding(GitCheck):
+    """Check the end of the first line of git commit messages.
+
+    The first line of git commit message should not end with a period.
+
+    H803 Commit message should not end with a period
+    """
+    name = "GitCheckCommitTitlePeriodEnding"
+
+    def run_once(self):
+        title = self._get_commit_title()
+
+        if title.rstrip().endswith('.'):
+            return (
+                1, 0,
+                "H803: git commit title ('%s') should not end with period"
+                % title.strip(),
+                self.name)
+
+
 class ProxyChecks(GlobalCheck):
     """Provide a mechanism for locally defined checks."""
     name = 'ProxyChecker'

setup.cfg

@@ -43,6 +43,7 @@ flake8.extension =
     H700 = hacking.core:hacking_localization_strings
     H801 = hacking.core:OnceGitCheckCommitTitleBug
     H802 = hacking.core:OnceGitCheckCommitTitleLength
+    H803 = hacking.core:OnceGitCheckCommitTitlePeriodEnding
     H901 = hacking.core:hacking_is_not
     H902 = hacking.core:hacking_not_in