skip patchsets which have empty subject

Summary:
Skip patchsets which have empty subject line as currently the logic provides empty line for the filter and returns all the patches.

Proper tests will be added later as we have to fix things first

Reviewed By: chantra

Differential Revision: D68493150

fbshipit-source-id: bbfaad5c896c20f2322195a6a1254bb78fa538d3

Author: vvfedorenko

kernel_patches_daemon/patchwork.py

@@ -751,6 +751,10 @@ async def get_relevant_subjects(self) -> Sequence[Subject]:
             all_series = await asyncio.gather(*tasks)
 
             for series in all_series:
+                if series.subject.strip() == "":
+                    logger.error(f"Malformed series name: {series.name}")
+                    err_malformed_series.add(1)
+                    continue
                 self.known_series[series.id] = series
 
                 if series.subject not in subjects: