kojiwrapper: Ignore warnings before task id

When looking for task ID in output of koji runroot command, do not check
just the first line. Instead look for first line that contains just a
number.

Most of the time, this should really be the first line. But if koji
client decides to print any warnings, this patch should skip that.

JIRA: RHELCMP-8944
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/test_koji_wrapper.py

@@ -668,6 +668,30 @@ class RunrootKojiWrapperTest(KojiWrapperBaseTestCase):
             ],
         )
 
+    @mock.patch("pungi.wrappers.kojiwrapper.run")
+    def test_run_runroot_cmd_with_warnings_before_task_id(self, run):
+        cmd = ["koji", "runroot", "--task-id"]
+        run.return_value = (0, "DeprecatioNWarning: whatever\n1234\n")
+        output = "Output ..."
+        self.koji._wait_for_task = mock.Mock(return_value=(0, output))
+
+        result = self.koji.run_runroot_cmd(cmd)
+        self.assertDictEqual(result, {"retcode": 0, "output": output, "task_id": 1234})
+        self.assertEqual(
+            run.call_args_list,
+            [
+                mock.call(
+                    cmd,
+                    can_fail=True,
+                    env={"FOO": "BAR", "PYTHONUNBUFFERED": "1"},
+                    buffer_size=-1,
+                    logfile=None,
+                    show_cmd=True,
+                    universal_newlines=True,
+                )
+            ],
+        )
+
     @mock.patch("shutil.rmtree")
     @mock.patch("tempfile.mkdtemp")
     @mock.patch("pungi.wrappers.kojiwrapper.run")