upload_symbols: tolerate a dedupe_queue which is None

On a heavily loaded system, the notify process might not exit in time,
so the logic to wait for it tries to use a queue which might not exist.

BUG=chromium:371915
TEST=Unit tests pass repeatedly

Change-Id: I8c724695c8045af2648f200424350abfe311defc
Reviewed-on: https://chromium-review.googlesource.com/199086
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Yu-Ju Hong <yjhong@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/upload_symbols.py b/scripts/upload_symbols.py
index 1ab568b..7cc3339 100644
--- a/scripts/upload_symbols.py
+++ b/scripts/upload_symbols.py
@@ -704,8 +704,12 @@
     # will kill us if we go silent for too long.
     wait_minutes = DEDUPE_NOTIFY_TIMEOUT
     while storage_notify_proc.is_alive() and wait_minutes > 0:
-      cros_build_lib.Info('waiting up to %i minutes for ~%i notifications',
-                          wait_minutes, dedupe_queue.qsize())
+      if dedupe_queue:
+        qsize = str(dedupe_queue.qsize())
+      else:
+        qsize = '[None]'
+      cros_build_lib.Info('waiting up to %i minutes for ~%s notifications',
+                          wait_minutes, qsize)
       storage_notify_proc.join(60)
       wait_minutes -= 1