avoid ImportError in test suite on python 3

python3 does not allow relative imports.

test/unit/__init.py__ and test/functional/__init.py__ already exist,
which means we can use absolute import on all versions of python
without resorting to http://legacy.python.org/dev/peps/pep-0328/

test/functional/fetch_tests.py

@@ -24,7 +24,7 @@ from os.path import join
 
 from tito.common import run_command
 from tito.compat import *
-from fixture import TitoGitTestFixture, tito
+from functional.fixture import TitoGitTestFixture, tito
 
 EXT_SRC_PKG = "extsrc"
 

test/functional/multiproject_tests.py

@@ -22,7 +22,7 @@ from os.path import join
 
 from tito.common import run_command, \
     get_latest_tagged_version, tag_exists_locally
-from fixture import *
+from functional.fixture import *
 
 # A location where we can safely create a test git repository.
 # WARNING: This location will be destroyed if present.

test/functional/release_yum_tests.py

@@ -22,7 +22,7 @@ import tempfile
 
 from os.path import join
 
-from fixture import TitoGitTestFixture, tito
+from functional.fixture import TitoGitTestFixture, tito
 
 from tito.compat import *
 

test/functional/singleproject_tests.py

@@ -14,7 +14,7 @@
 
 import os
 from tito.common import *
-from fixture import TitoGitTestFixture, tito
+from functional.fixture import TitoGitTestFixture, tito
 
 #TITO_REPO = os.path.dirname(os.path.dirname(os.path.dirname(__file__)))
 PKG_NAME = "titotestpkg"

test/unit/pep8-tests.py

@@ -22,7 +22,7 @@ http://docs.python.org/3.3/reference/lexical_analysis.html
 """
 
 import pep8
-from fixture import *
+from unit.fixture import *
 
 
 class TestPep8(TitoUnitTestFixture):