Use unittest2 if available

The module backports features to Python 2.6 and 2.7. If it is available,
the tests will use it. If it is not available, it will fall back to
regular unittest. On Python 2.7, the tests pass anyway. On Python 2.6,
there are failures with Python 2.6.

Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>

tests/helpers.py

@@ -2,7 +2,10 @@
 
 import mock
 import os
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import tempfile
 import shutil
 import errno

tests/test_buildinstall.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import mock
 
 import os

tests/test_checks.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 import mock
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import os
 import sys
 import StringIO

tests/test_compose.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 import mock
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import os
 import sys
 import tempfile

tests/test_createiso_phase.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import mock
 
 import os

tests/test_createrepo_wrapper.py

@@ -1,7 +1,10 @@
 #!/usr/bin/env python2
 # -*- coding: utf-8 -*-
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 
 import os
 import sys

tests/test_createrepophase.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import mock
 
 import os

tests/test_imagebuildphase.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import mock
 
 import os

tests/test_imagechecksumphase.py

@@ -1,8 +1,10 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import mock
 
 import os

tests/test_koji_wrapper.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 import mock
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import tempfile
 
 import os

tests/test_lorax_wrapper.py

@@ -1,7 +1,10 @@
 #!/usr/bin/env python2
 # -*- coding: utf-8 -*-
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 
 import os
 import sys

tests/test_pkgset_pkgsets.py

@@ -4,7 +4,10 @@
 import mock
 import os
 import sys
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import json
 import tempfile
 

tests/test_scm.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 import mock
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import shutil
 import tempfile
 

tests/test_test_phase.py

@@ -2,7 +2,10 @@
 # -*- coding: utf-8 -*-
 
 
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 
 import os
 import sys

tests/test_util.py

@@ -4,7 +4,10 @@
 import mock
 import os
 import sys
-import unittest
+try:
+    import unittest2 as unittest
+except ImportError:
+    import unittest
 import tempfile
 import shutil