ALBS-732: pungi: do not build anything if unsigned packages found

- Fix unittests

pungi/phases/pkgset/pkgsets.py

@@ -850,8 +850,6 @@ class KojiMockPackageSet(PackageSetBase):
         self.extra_builds = extra_builds or []
         self.extra_tasks = extra_tasks or []
         self.reuse = None
-        self.sigkey_ordering = [sigkey.lower() for sigkey in sigkey_ordering] \
-            or [None]
 
     def __getstate__(self):
         result = self.__dict__.copy()
@@ -971,6 +969,10 @@ class KojiMockPackageSet(PackageSetBase):
     def _is_rpm_signed(self, rpm_path) -> bool:
         ts = rpm.TransactionSet()
         ts.setVSFlags(rpm._RPMVSF_NOSIGNATURES)
+        sigkeys = [
+            sigkey.lower() for sigkey in self.sigkey_ordering
+            if sigkey is not None
+        ]
         with open(rpm_path, 'rb') as fd:
             header = ts.hdrFromFdno(fd)
             signature = header[rpm.RPMTAG_SIGGPG] or header[rpm.RPMTAG_SIGPGP]
@@ -978,7 +980,7 @@ class KojiMockPackageSet(PackageSetBase):
                 return False
             pgp_msg = pgpy.PGPMessage.from_blob(signature)
             return any(
-                signature.signer.lower() in self.sigkey_ordering
+                signature.signer.lower() in sigkeys
                 for signature in pgp_msg.signatures
             )