Add another debugging bit for reply-to matching

Signed-off-by: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
diff --git a/src/bugspray/__init__.py b/src/bugspray/__init__.py
index bb50b64..522b4a4 100644
--- a/src/bugspray/__init__.py
+++ b/src/bugspray/__init__.py
@@ -595,9 +595,10 @@
 
     msgids = list()
     for pair in pairs:
-        if pair[1] not in msgids:
+        if pair[1].strip() and pair[1] not in msgids:
             msgids.append(pair[1])
 
+    logger.debug('msgids=%s', str(msgids))
     return msgids