Android buildbot - halt build if subcommand returns error

Android buildbot - halt build if subcommand returns error

bb_run_bot is currently ORing the return codes of each
subcommand but not early terminating.  That means that if
a command returns an error, it does not explicitly mark
that step as failing. The quickest fix is to early terminate,
which is correct for the current usage of bb_run_bot, where
subcommands do not return non-zero status except on
serious error.

Example problematic build:
http://build.chromium.org/p/chromium.linux/builders/Android%20Tests/builds/1479
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=183776

[Yaron, 2013-02-21 02:02:49]

https://chromiumcodereview.appspot.com/12324007/diff/1/buildbot/bb_run_bot.py
File buildbot/bb_run_bot.py (right):

https://chromiumcodereview.appspot.com/12324007/diff/1/buildbot/bb_run_bot.py...
buildbot/bb_run_bot.py:198: 
Shouldn't it return 0 at the end if we reach it?

[Isaac (away), 2013-02-21 02:10:37]

It could, but it is implicit.  

If it doesn't early terminate, main() will return None.  At the bottom, we call
sys.exit with the return value, and sys.exit treats None as 0
(http://docs.python.org/2/library/sys.html#sys.exit).

[Yaron, 2013-02-21 02:12:53]

lgtm