autotest: Add optional isolate downloading

This makes it possible to rely on an isolate rather than a provided URL
to fetch the SSP contents from. If provided, it supersedes and obviates
the package URL; if not provided, behavior is unchanged.

BUG=chromium:842255
TEST=Ran test scripts with and without the arg

Change-Id: I51aff2228ce1a0162e58b1183b3c1899deadea17
Reviewed-on: https://chromium-review.googlesource.com/1150933
Commit-Ready: Jacob Kopczynski <jkop@chromium.org>
Tested-by: Jacob Kopczynski <jkop@chromium.org>
Reviewed-by: Jacob Kopczynski <jkop@chromium.org>
diff --git a/server/autoserv b/server/autoserv
index 6fd9d31..8111c3f 100755
--- a/server/autoserv
+++ b/server/autoserv
@@ -43,7 +43,6 @@
 
 _CONFIG = global_config.global_config
 
-
 # Number of seconds to wait before returning if testing mode is enabled
 TESTING_MODE_SLEEP_SECS = 1
 
@@ -173,7 +172,8 @@
         test_container = bucket.setup_test(container_id, job_id, ssp_url,
                                            results, control=control,
                                            job_folder=job_folder,
-                                           dut_name=dut_name)
+                                           dut_name=dut_name,
+                                           isolate_hash=parser.options.isolate)
     except Exception as e:
         job.record('FAIL', None, None,
                    'Failed to setup container for test: %s. Check logs in '