This reverts commit f4913068.

Reason for revert: panics, see b/119830955

Original change's description:
> [vpython] Roll to pick up user differentiation of cached envs.
> 
> R=​vadimsh@chromium.org
> 
> Bug: 869227
> Change-Id: I7e529c7c4d63e35a66ef93623982afc7d254d72f
> Reviewed-on: https://chromium-review.googlesource.com/c/1344638
> Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
> Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>
> Auto-Submit: Robbie Iannucci <iannucci@chromium.org>
> Reviewed-by: Vadim Shtayura <vadimsh@chromium.org>

TBR=iannucci@chromium.org,vadimsh@chromium.org

Change-Id: Ie77d559dc1787ec1b8a19076238b7018d39dd0b5
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 869227
Reviewed-on: https://chromium-review.googlesource.com/c/1344639Reviewed-by: Vadim Shtayura <vadimsh@chromium.org>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>