client: make log helpful if PermissionError happens
client: make log helpful if PermissionError happens

Bug: 1239809
Change-Id: I6a0063a48fb9b20063b7f54b728fb0aa28347873
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/3103565
Auto-Submit: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>
Commit-Queue: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Reviewed-by: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py