Small fix to prevent this test from interfering with others.

lib/spack/spack/test/unit_install.py

@@ -79,12 +79,16 @@ def setUp(self):
         pkgX.installed = False
         pkgY.installed = False
 
+        self.saved_db = spack.db
         pkgDb = MockPackageDb({specX:pkgX, specY:pkgY})
         spack.db = pkgDb
 
+
     def tearDown(self):
         super(UnitInstallTest, self).tearDown()
 
+        spack.db = self.saved_db
+
     def test_installing_both(self):
         mo = MockOutput()
 
@@ -96,6 +100,7 @@ def test_installing_both(self):
             {bIdX:test_install.TestResult.PASSED,
             bIdY:test_install.TestResult.PASSED})
 
+
     def test_dependency_already_installed(self):
         mo = MockOutput()
 
@@ -107,6 +112,7 @@ def test_dependency_already_installed(self):
 
     #TODO: add test(s) where Y fails to install
 
+
 class MockPackageDb(object):
     def __init__(self, init=None):
         self.specToPkg = {}
@@ -118,4 +124,3 @@ def get(self, spec):
 
 def test_fetch_log(path):
     return []
-