This is my installation error:

Building extension modules
Traceback (most recent call last):
  File "setup.py", line 8, in <module>
    import petsc4py
ImportError: No module named 'petsc4py'
    Linting firedrake codebase
    Linting firedrake test suite
    Linting firedrake scripts
    Running all regression tests
Traceback (most recent call last):
  File "/usr/lib/python3.5/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.5/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/emmanuel/firedrake/lib/python3.5/site-packages/pytest.py", line 7, in <module>
    from _pytest.assertion import register_assert_rewrite
  File "/home/emmanuel/firedrake/lib/python3.5/site-packages/_pytest/assertion/__init__.py", line 12, in <module>
    from _pytest.assertion import rewrite
  File "/home/emmanuel/firedrake/lib/python3.5/site-packages/_pytest/assertion/rewrite.py", line 24, in <module>
    from _pytest.pathlib import fnmatch_ex
  File "/home/emmanuel/firedrake/lib/python3.5/site-packages/_pytest/pathlib.py", line 26, in <module>
    from pathlib2 import Path, PurePath
ImportError: No module named 'pathlib2'
Makefile:60: recipe for target 'test' failed
make: *** [test] Error 1
(firedrake) emmanuel@emmanuel:~/firedrake/src/firedrake$
(firedrake) emmanuel@emmanuel:~/firedrake/src/firedrake$
(firedrake) emmanuel@emmanuel:~/firedrake/src/firedrake$
(firedrake) emmanuel@emmanuel:~/firedrake/src/firedrake$ sudo su
[sudo] senha para emmanuel:
root@emmanuel:/home/emmanuel/firedrake/src/firedrake#
root@emmanuel:/home/emmanuel/firedrake/src/firedrake#
root@emmanuel:/home/emmanuel/firedrake/src/firedrake#
root@emmanuel:/home/emmanuel/firedrake/src/firedrake# make alltest
    Building extension modules
Traceback (most recent call last):
  File "setup.py", line 31, in <module>
    import versioneer
  File "/home/emmanuel/firedrake/src/firedrake/versioneer.py", line 1658
    file=sys.stderr)
        ^
SyntaxError: invalid syntax
    Linting firedrake codebase
/usr/bin/python: No module named flake8
Makefile:8: recipe for target 'lint' failed
make: *** [lint] Error 1