backend: recreate missing repodata so that prunerepo doesn't traceback

Fix fedora-copr#2926

backend/run/copr_prune_results.py

@@ -81,6 +81,13 @@ def run_prunerepo(chroot_path, username, projectdir, sub_dir_name, prune_days,
     """
     try:
         LOG.info("Pruning of %s/%s/%s started", username, projectdir, sub_dir_name)
+
+        repodata = os.path.join(chroot_path, "repodata")
+        if not os.path.exists(repodata):
+            LOG.info("Recreating missing repodata for %s/%s/%s",
+                     username, projectdir, sub_dir_name)
+            call_copr_repo(directory=chroot_path, logger=LOG, appstream=appstream)
+
         all_rpms = get_rpms_to_remove(chroot_path, days=prune_days, log=LOG)
 
         # See https://github.com/fedora-copr/copr/issues/1817 for more info

backend/tests/test_modifyrepo.py

@@ -584,16 +584,16 @@ def test_pruner_arg_max(self, patched_get_rpms):
             patched_popen.return_value.communicate.return_value = ("","")
             patched_popen.return_value.returncode = 0
             run_prunerepo("/tmp", "blah", "blah", "blah", 0, False)
-            first_call = patched_popen.call_args_list[0][0][0]
-            assert len(patched_popen.call_args_list) == 2
+            call = patched_popen.call_args_list[1][0][0]
+            assert len(patched_popen.call_args_list) == 3
 
-        assert list == type(first_call)
-        assert 1000 < len(first_call) < 9000*2+100
+        assert list == type(call)
+        assert 1000 < len(call) < 9000*2+100
         # Test we can execute.
-        subprocess.check_call(["/bin/true"] + first_call)
+        subprocess.check_call(["/bin/true"] + call)
 
         opts = ["--rpms-to-remove", rpm_name] * 9000
-        assert first_call == ["copr-repo", "--batched", "/tmp"] + opts + ["--no-appstream-metadata"]
+        assert call == ["copr-repo", "--batched", "/tmp"] + opts + ["--no-appstream-metadata"]
 
     @pytest.mark.parametrize('run_bg', [True, False])
     @mock.patch.dict(os.environ, {'COPR_TESTSUITE_NO_OUTPUT': '1'})