tree d510d2b1301c52b32cbf7e13a6db89df34754342
parent 91a66c819d7ab3816ddbf7799cfeb0d593a6d268
author Rob Mohr <mohrr@google.com> 1577999388 -0800
committer Rob Mohr <mohrr@google.com> 1577999388 -0800

Run single presubmit steps.

Add ability to run single presubmit steps instead of always
running everything.

Many small fixes:
* add CIPD lib directories to LD_LIBRARY_PATH
* set PW_ROOT (pretty sure not needed but matches user workflows)
* set VIRTUAL_ENV
* add "--editable=" to pip install (it's inexplicably required)
* search for Pigweed Python packages without Pigweed environment
  (the virtualenv seems to screw with vpython)
* install from Pigweed requirements.txt

Bug: 3, 29
Change-Id: I549d7820015f79d315de43e7cfca4c692ace1c96