[autotest] Update test push to allow specifying web server.

Sometimes the default stable version specified in cautotest doesn't have
all the build artifacts we need for validating the tests so let's
default point to the test server so we can minimize flake due to the
default version being bumped in prod.

BUG=None
TEST=unittest --debug autotest_lib.site_utils.test_push_unittest

Change-Id: I51ceb734fb735fe6c789cfd5c470e715513fb83d
Reviewed-on: https://chromium-review.googlesource.com/420471
Tested-by: Kevin Cheng <kevcheng@chromium.org>
Trybot-Ready: Kevin Cheng <kevcheng@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Commit-Queue: Kevin Cheng <kevcheng@chromium.org>
diff --git a/site_utils/test_push_unittest.py b/site_utils/test_push_unittest.py
index c4e18c0..5b100dc 100755
--- a/site_utils/test_push_unittest.py
+++ b/site_utils/test_push_unittest.py
@@ -62,9 +62,9 @@
         urllib2.urlopen(mox.IgnoreArg()).AndReturn(response)
 
         self.mox.StubOutWithMock(test_push, 'get_default_build')
-        test_push.get_default_build(mox.IgnoreArg()).AndReturn(
+        test_push.get_default_build(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(
                 'stumpy-release/R36-5881-0.0')
-        test_push.get_default_build(mox.IgnoreArg()).AndReturn(
+        test_push.get_default_build(mox.IgnoreArg(), mox.IgnoreArg()).AndReturn(
                 'quawks-release/R36-5881-0.0')
 
         self.mox.StubOutWithMock(test_push, 'check_dut_image')