Improve robustness of env test in parallel

lib/spack/spack/test/cmd/uninstall.py

@@ -227,6 +227,9 @@ class TestUninstallFromEnv(object):
     def environment_setup(
         self, mutable_mock_env_path, config, mock_packages, mutable_database, install_mockery
     ):
+        # make environments local to each instantiation of the fixture so they don't clash
+        # in parallel
+        spack.config.set("config:environments_root", str(tmpdir.join("envs")))
         TestUninstallFromEnv.env("create", "e1")
         e1 = spack.environment.read("e1")
         with e1: