[PATCH stable] tests: add support in run-tests.py for an environment variable to stop color

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1501106204 14400
#      Wed Jul 26 17:56:44 2017 -0400
# Branch stable
# Node ID bf9183f48b08e1bde191139b0c83b766fe13cba5
# Parent  99277f2f93979456860e5a619b819b64e813b81c
tests: add support in run-tests.py for an environment variable to stop color

I don't like the color output, so this gives me a way to easily never
see it while still having pygments on my machine.

diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -269,7 +269,7 @@ def getparser():
     parser.add_option("-c", "--cover", action="store_true",
         help="print a test coverage report")
     parser.add_option("--color", choices=["always", "auto", "never"],
-                      default="auto",
+                      default=os.environ.get('HGRUNTESTSCOLOR', 'auto'),
                       help="colorisation: always|auto|never (default: auto)")
     parser.add_option("-d", "--debug", action="store_true",
         help="debug mode: write output of test scripts to console"