tell upstart to reload configuration after writing an upstart job

Invoking 'initctl reload-configuration' is only required if inotify 
does not work.  overlayroot does not support inotify.  So, we just
call initctl always, which wont hurt anything.

cloudinit/handlers/upstart_job.py

@@ -64,3 +64,7 @@ class UpstartJobPartHandler(handlers.Handler):
         payload = util.dos2unix(payload)
         path = os.path.join(self.upstart_dir, filename)
         util.write_file(path, payload, 0644)
+
+        # if inotify support is not present in the root filesystem
+        # (overlayroot) then we need to tell upstart to re-read /etc 
+        util.subp(["initctl", "reload-configuration"], capture=False)

tests/unittests/test_builtin_handlers.py

@@ -6,6 +6,7 @@ from mocker import MockerTestCase
 
 from cloudinit import handlers
 from cloudinit import helpers
+from cloudinit import util
 
 from cloudinit.handlers import upstart_job
 
@@ -34,6 +35,7 @@ class TestBuiltins(MockerTestCase):
         self.assertEquals(0, len(os.listdir(up_root)))
 
     def test_upstart_frequency_single(self):
+        # files should be written out when frequency is ! per-instance
         c_root = self.makeDir()
         up_root = self.makeDir()
         paths = helpers.Paths({
@@ -41,9 +43,12 @@ class TestBuiltins(MockerTestCase):
             'upstart_dir': up_root,
         })
         freq = PER_INSTANCE
+
+        mock_subp = self.mocker.replace(util.subp, passthrough=False)
+        mock_subp(["initctl", "reload-configuration"], capture=False)
+        self.mocker.replay()
+
         h = upstart_job.UpstartJobPartHandler(paths)
-        # No files should be written out when
-        # the frequency is ! per-instance
         h.handle_part('', handlers.CONTENT_START,
                       None, None, None)
         h.handle_part('blah', 'text/upstart-job',