protonmsg: don't send rpm.sign messages when the sigkey is empty

When a build completes, we store the original, unsigned rpm headers
to disk. This results in the postRPMSign callback being called, and
a rpm.sign message being sent with an empty sigkey. The intended
sematics of the rpm.sign message is to notify a service when an rpm
has been signed. Therefore, we should not be sending a message when
the sigkey is empty.

plugins/hub/protonmsg.py

@@ -196,6 +196,8 @@ def prep_import(cbtype, *args, **kws):
 @convert_datetime
 @callback('postRPMSign')
 def prep_rpm_sign(cbtype, *args, **kws):
+    if not kws['sigkey']:
+        return
     address = 'sign.rpm'
     props = {'type': cbtype[4:],
              'sigkey': kws['sigkey'],

tests/test_plugins/test_protonmsg.py

@@ -123,6 +123,18 @@ class TestProtonMsg(unittest.TestCase):
                        rpm_version=rpm['version'], rpm_release=rpm['release'],
                        **build)
 
+    def test_prep_rpm_sign_no_sigkey(self):
+        build = {'name': 'test-pkg',
+                 'version': '1.0',
+                 'release': '1'}
+        rpm = {'name': 'test-pkg-subpkg',
+               'version': '2.0',
+               'release': '2'}
+        sigkey = ''
+        protonmsg.prep_rpm_sign('postRPMSign', sigkey=sigkey, sighash='fedcba9876543210',
+                                build=build, rpm=rpm)
+        self.assertFalse(hasattr(context, 'protonmsg_msgs'))
+
     def test_prep_tag(self):
         build = {'name': 'test-pkg', 'version': '1.0', 'release': '1'}
         protonmsg.prep_tag('postTag', tag={'name': 'test-tag'},