Run NetXNG::Flush() to flush any write cache before checking the file

size

Flush() is void and we just continue even if there is an error

src/TJAlienFile.cxx

@@ -510,6 +510,7 @@ void TJAlienFile::Close(Option_t * option)
     // If WRITE operation we need to commit the LFN and PFN to the catalogue
     TString command("commit");
 
+    TAliceFile::Flush();
     Long64_t siz = GetSize();
 
     // Close file