V8 Buildbot: Fix tester revision from builders triggered by the nightly scheduler.
V8 Buildbot: Fix tester revision from builders triggered by the nightly scheduler.

BUG=315202

Review URL: https://codereview.chromium.org/314933003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@276330 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build