Revert of Whitelist environment entering recipe engine to match run_slave. (patchset #2 id:20001 of https://codereview.chromium.org/1252053002/)
Revert of Whitelist environment entering recipe engine to match run_slave. (patchset #2 id:20001 of https://codereview.chromium.org/1252053002/)

Reason for revert:
Doesn't include BUILDBOT_* magic env vars. Caused crbug.com/513109

Original issue's description:
> Whitelist environment entering recipe engine to match run_slave.
> 
> This is mainly for local run_recipe invocations, that we don't accidentally
> incorporate environment variables that won't be available on the bots, such
> as GYP defines.
> 
> BUG=392992
> 
> Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=296090

TBR=akeshet@chromium.org,luqui@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=392992

Review URL: https://codereview.chromium.org/1252513003

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@296092 0039d316-1c4b-4281-b951-d872f2087c98

luci/recipes-py,shishkander/recipes-py,shishkander/recipes-py,luci/recipes-py