V8 Buildbot: Auto-bisect - fix fetching builds for testers.
V8 Buildbot: Auto-bisect - fix fetching builds for testers.

BUG=chromium:511215
TBR=tandrii@chromium.org

Review URL: https://codereview.chromium.org/1358103002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@296813 0039d316-1c4b-4281-b951-d872f2087c98

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