Work around cygwin / python 2.6 old installs.
Work around cygwin / python 2.6 old installs.

This is really just needed during the initial bootstrap; the difference here is
that python 2.6 zipfile doesn't support with statement.

R=vadimsh@chromium.org
BUG=

Review URL: https://codereview.appspot.com/169770043

madecoste/swarming,pombreda/swarming,madecoste/swarming,madecoste/swarming,madecoste/swarming,pombreda/swarming,luci/luci-py,pombreda/swarming,luci/luci-py,luci/luci-py,pombreda/swarming,luci/luci-py