minor change to optim, if file hash is same but we have no thumb, then try to gen one anyway

pa_job_manager.py

@@ -1314,7 +1314,8 @@ def GenHashAndThumb(job, e):
         return
 
     new_hash = md5( job, e.FullPathOnFS() )
-    if new_hash == e.file_details.hash:
+    # same hash and we already have a thumbnail-> just return
+    if new_hash == e.file_details.hash and e.file_details.thumbnail:
         if DEBUG:
             print(f"OPTIM: GenHashAndThumb {e.name} md5 is same - likely a mv on filesystem so skip md5/thumb")
         job.current_file_num+=1