Fix crash when pkgset phase is skipped

JIRA: COMPOSE-3832
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

pungi/phases/createrepo.py

@@ -70,7 +70,7 @@ class CreaterepoPhase(PhaseBase):
     def run(self):
         get_productids_from_scm(self.compose)
         reference_pkgset = None
-        if self.pkgset_phase:
+        if self.pkgset_phase and self.pkgset_phase.package_sets:
             reference_pkgset = self.pkgset_phase.package_sets[-1]
         for i in range(self.compose.conf['createrepo_num_threads']):
             self.pool.add(
@@ -109,7 +109,9 @@ def create_variant_repo(compose, arch, variant, pkg_type, pkgset, modules_metada
     createrepo_c = compose.conf["createrepo_c"]
     createrepo_checksum = compose.conf["createrepo_checksum"]
     repo = CreaterepoWrapper(createrepo_c=createrepo_c)
-    repo_dir_arch = pkgset.paths["global" if pkg_type == "srpm" else arch]
+    repo_dir_arch = None
+    if pkgset:
+        repo_dir_arch = pkgset.paths["global" if pkg_type == "srpm" else arch]
 
     try:
         repo_dir = types[pkg_type][1]()

pungi/phases/pkgset/__init__.py

@@ -21,6 +21,10 @@ class PkgsetPhase(PhaseBase):
     """PKGSET"""
     name = "pkgset"
 
+    def __init__(self, *args, **kwargs):
+        super(PkgsetPhase, self).__init__(*args, **kwargs)
+        self.package_sets = []
+
     def run(self):
         pkgset_source = "PkgsetSource%s" % self.compose.conf["pkgset_source"]
         from .source import PkgsetSourceContainer