Added check for special case when user is in .git directory

[thegalah]

No description provided.

[derekbekoe]

Unless there's something I'm missing, I suspect the _is_inside_git_directory method doesn't work as intended.

[derekbekoe]

I just tried the command you run and got the following:

$ git rev-parse --is-inside-git-dir
false
$ cd .git
$ git rev-parse --is-inside-git-dir
true
$ 

So the git command returns a string.

This method should return a boolean rather than a string.
i.e. you could have something like:

git_result = is_inside_git_dir.decode('utf-8').strip()
if git_result == 'false':
    return False
elif git_result == 'true':
    return True
else:
    raise CLIError(...)

[thegalah]

added this fix