clear test cache before and after each MockPackagesTest (I think Ive got a better way to avoid test fragility but Ill add this for now)

lib/spack/spack/cmd/test.py

@@ -70,4 +70,4 @@ def test(parser, args):
         spack.cache_path = join_path(spack.var_path, "test-cache")
         mkdirp(spack.cache_path)
         spack.test.run(args.names, outputDir, args.verbose)
-        shutil.rmtree(spack.cache_path)
+        shutil.rmtree(spack.cache_path, ignore_errors=True)

lib/spack/spack/test/git_fetch.py

@@ -30,9 +30,6 @@
 from spack.test.mock_repo import MockGitRepo
 from spack.version import ver
 
-import shutil
-import os
-
 class GitFetchTest(MockPackagesTest):
     """Tests fetching from a dummy git repository."""
 
@@ -51,8 +48,6 @@ def tearDown(self):
         """Destroy the stage space used by this test."""
         super(GitFetchTest, self).tearDown()
         self.repo.destroy()
-        for d in os.listdir(spack.cache_path):
-            shutil.rmtree(os.path.join(spack.cache_path, d))
 
     def assert_rev(self, rev):
         """Check that the current git revision is equal to the supplied rev."""

lib/spack/spack/test/mock_packages_test.py

@@ -125,9 +125,16 @@ def cleanmock(self):
             pkg.dependencies.update(deps)
 
 
+    def rm_cache(self):
+        shutil.rmtree(spack.cache_path, ignore_errors=True)
+
+
     def setUp(self):
+        self.rm_cache()
+        mkdirp(spack.cache_path)
         self.initmock()
 
 
     def tearDown(self):
+        self.rm_cache()
         self.cleanmock()