Fixes to support Python 2.6 again.

Details:

- Added Python 2.6 again to .travis.yml (it was removed in commit 4486bcb).

- Replaced the use of dictionary comprehensions in `git/cmd.py` around
  line 800 with the code before that change (in commit 25a2ebf).
  Reason: dict comprehensions were introduced only in Python 2.7.

- Changed the import source for `SkipTest` and `skipIf` from `unittest.case`
  to first trying `unittest` and upon ImportError from `unittest2`.
  This was done in `git/util.py` and in several testcases.
  Reason: `SkipTest` and `skipIf` were introduced to unittest only
  in Python 2.7, and `unittest2` is a backport of `unittest` additions
  to Python 2.6.

- In git/test/lib/helper.py, fixed the definition of `assertRaisesRegex`
  to work on py26.

- For Python 2.6, added the `unittest2` dependency to `requirements.txt`
  and changed `.travis.yml` to install `unittest2`. Because git/util.py
  uses SkipTest from unittest/unittest2, the dependency could not be added
  to `test-requirements.txt`.

- Fixed an assertion in `git/test/test_index.py` to also allow
  a Python 2.6 specific exception message.

- In `is_cygwin_git()` in `git/util.py`, replaced `check_output()` with
  `Popen()`. It was added in Python 2.7.

- Enabled Python 2.6 for Windows:

  - Added Python 2.6 for MINGW in .appveyor.yml.

  - When defining `PROC_CREATIONFLAGS` in `git/cmd.py`, made use of certain
    win32 and subprocess flags that were introduced in Python 2.7, dependent
    on whether we run on Python 2.7 or higher.

  - In `AutoInterrupt.__del__()` in `git/cmd.py`, allowed for `os` not having
    `kill()`. `os.kill()` was added for Windows in Python 2.7 (For Linux, it
    existed in Python 2.6 already).

1 files changed, 11 insertions, 4 deletions

diff --git a/git/util.py b/git/util.py
index 1e0d3eb4..6e3ddfab 100644
--- a/git/util.py
+++ b/git/util.py
@@ -11,11 +11,15 @@ import getpass
 import logging
 import os
 import platform
+import subprocess
 import re
 import shutil
 import stat
 import time
-from unittest.case import SkipTest
+try:
+    from unittest import SkipTest
+except ImportError:
+    from unittest2 import SkipTest
 
 from gitdb.util import (# NOQA @IgnorePep8
     make_sha,
@@ -303,7 +307,7 @@ def is_cygwin_git(git_executable):
     if not is_win:
         return False
 
-    from subprocess import check_output
+    #from subprocess import check_output
 
     is_cygwin = _is_cygwin_cache.get(git_executable)
     if is_cygwin is None:
@@ -316,8 +320,11 @@ def is_cygwin_git(git_executable):
 
             ## Just a name given, not a real path.
             uname_cmd = osp.join(git_dir, 'uname')
-            uname = check_output(uname_cmd, universal_newlines=True)
-            is_cygwin = 'CYGWIN' in uname
+            process = subprocess.Popen([uname_cmd], stdout=subprocess.PIPE,
+                                       universal_newlines=True)
+            uname_out, _ = process.communicate()
+            #retcode = process.poll()
+            is_cygwin = 'CYGWIN' in uname_out
         except Exception as ex:
             log.debug('Failed checking if running in CYGWIN due to: %r', ex)
         _is_cygwin_cache[git_executable] = is_cygwin