Change-Id: Ib5617612be38bb6d7dafcb2edab887c998a676ab
BUG=chromium-os:12951
TEST=Ran it with Simple. Saw logs generated (1_update) and in root/dev_server.log. Ran unittests for cros_build_lib.
Review URL: http://codereview.chromium.org/6672007
This reintroduces the change after commit 3635aaa55e, which reverted 01c8423582.
BUG=chromium-os:11717
TEST=Ran new unit tests, and did full build.
Review URL: http://codereview.chromium.org/6579048
Change-Id: I598e459ddaa156af47d47d0482cac16ce44f07a4
extra noise in the final exception output.
This change stops catching and rethrowing the same exception, and generally
makes the RunCommand slightly more readable (if longer).
Some unit tests are added, but they only test RunCommand, and not all options
to RunCommand.
BUG=chromium-os:11717
TEST=Manual, and new lib/cros_build_lib_unittest
Review URL: http://codereview.chromium.org/6576016
Change-Id: Ibe9b13ff302621e93196008f86914cb65a232d61