Proper subprocess exit code handling for apply_svn_patch.py
Proper subprocess exit code handling for apply_svn_patch.py

This fixes the lack of wait() call for the involved subprocesses.
Without it, they weren't given time to finish execution properly,
resulting in None returncodes, which failed the execution of the
script.

BUG=312827
TEST=manual execution on a real bot, where different invalid parameters
triggered each subprocess to fail, after which I verified the script exit code.

Review URL: https://codereview.chromium.org/148313002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@247239 0039d316-1c4b-4281-b951-d872f2087c98

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