Shorten nox virtualenv names to avoid hashing. (#3585)

Author: tseaver

packages/google-cloud-vision/nox.py

@@ -27,6 +27,9 @@ def unit_tests(session, python_version):
     # Run unit tests against all supported versions of Python.
     session.interpreter = 'python{}'.format(python_version)
 
+    # Set the virtualenv dirname.
+    session.virtualenv_dirname = 'unit-' + python_version
+
     # Install all test dependencies, then install this package in-place.
     session.install('mock', 'pytest', 'pytest-cov', '../core/')
     session.install('-e', '.')
@@ -51,6 +54,9 @@ def system_tests(session, python_version):
     # Run unit tests against all supported versions of Python.
     session.interpreter = 'python{}'.format(python_version)
 
+    # Set the virtualenv dirname.
+    session.virtualenv_dirname = 'sys-' + python_version
+
     # Install all test dependencies, then install this package in-place.
     session.install('pytest', '../core/', '../storage/')
     session.install('../test_utils/')
@@ -105,6 +111,10 @@ def lint(session):
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
     session.interpreter = 'python3.6'
+
+    # Set the virtualenv dirname.
+    session.virtualenv_dirname = 'setup'
+
     session.install('docutils', 'pygments')
     session.run(
         'python', 'setup.py', 'check', '--restructuredtext', '--strict')