Merge pull request #198 from johnpaulalex/gitdir

Replace a lot of chdir's with git -C $dirname

There are still some left in the code.

There are still 6 calls to os.getcwd in manic/ (at least 1 is ok, the one in checkout.py), and 6 calls to os.chdir (2 in repository_svn, 4 in sourcetree). At least some of those can probably go away too.

And loads of dependencies on cwd in test/ code, but many if not all could be fixed in the same way (with the -C option)

User interface changes?: No

Fixes: No

Testing:
test removed: no
unit tests: 'make utest'
system tests: 'make stest'
manual testing: none

manic/externals_description.py

@@ -151,9 +151,8 @@ def git_submodule_status(repo_dir):
     """Run the git submodule status command to obtain submodule hashes.
         """
     # This function is here instead of GitRepository to avoid a dependency loop
-    cwd = os.getcwd()
-    os.chdir(repo_dir)
-    cmd = ['git', 'submodule', 'status']
+    cmd = 'git -C {repo_dir} submodule status'.format(
+        repo_dir=repo_dir).split()
     git_output = execute_subprocess(cmd, output_to_caller=True)
     submodules = {}
     submods = git_output.split('\n')
@@ -168,7 +167,6 @@ def git_submodule_status(repo_dir):
 
             submodules[items[1]] = {'hash':items[0], 'status':status, 'tag':tag}
 
-    os.chdir(cwd)
     return submodules
 
 def parse_submodules_desc_section(section_items, file_path):