Don't fail if we try to look for a build we haven't seen yet.
Don't fail if we try to look for a build we haven't seen yet.

BUG=391553
TBR=eseidel@chromium.org

Review URL: https://codereview.chromium.org/375433002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@281466 0039d316-1c4b-4281-b951-d872f2087c98

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