[autotest] Bug fix in autoupdate_EndToEndTest

The bug was introduced in CL 276168.

BUG=chromium:502343
TEST=local run the test
http://dshi/results/2071-debug_user/172.27.215.232/autoupdate_EndToEndTest.paygen_au_canary_test_delta/debug/autoupdate_EndToEndTest.paygen_au_canary_test_delta.DEBUG
06/19 11:53:05.357 DEBUG|autoupdate_EndToEn:1413| Choose least loaded devserver: http://172....:8082
06/19 11:53:05.358 INFO |autoupdate_EndToEn:1040| Staging images onto autotest devserver (http://172....:8082)

Change-Id: Ib830f79db63278f177b65da37c97ab14c55954be
Reviewed-on: https://chromium-review.googlesource.com/280608
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
1 file changed