[PATCH 1 of 2] tests: use $PYTHON in #! so we always use the right Python

[Yuya Nishihara]

On Sun, 18 Jun 2017 22:16:12 -0400, Augie Fackler wrote:
> # HG changeset patch
> # User Augie Fackler <augie at google.com>
> # Date 1497551272 14400
> #      Thu Jun 15 14:27:52 2017 -0400
> # Node ID 6b14e1abca3dcb131c7765c41f30e903d72e1faa
> # Parent  2851b24eecc483ce1546d63d155fa2e9250e3f44
> tests: use $PYTHON in #! so we always use the right Python

Queued, thanks.