publish_tarball: fix crash on unicode value
publish_tarball: fix crash on unicode value

BUG=433338

Review URL: https://codereview.chromium.org/1178493003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@295601 0039d316-1c4b-4281-b951-d872f2087c98

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