Do not leak environment and home directory in documentation

Fixes #1329

docs/source/powerline_autodoc.py

@@ -1,6 +1,8 @@
 # vim:fileencoding=utf-8:noet
 from __future__ import (unicode_literals, division, absolute_import, print_function)
 
+import os
+
 from inspect import formatargspec
 
 from sphinx.ext import autodoc
@@ -29,6 +31,34 @@ class ThreadedDocumenter(autodoc.FunctionDocumenter):
 		return formatargspec(*argspec, formatvalue=formatvalue).replace('\\', '\\\\')
 
 
+class Repr(object):
+	def __init__(self, repr_contents):
+		self.repr_contents = repr_contents
+
+	def __repr__(self):
+		return '<{0}>'.format(self.repr_contents)
+
+
+class EnvironDocumenter(autodoc.AttributeDocumenter):
+	@classmethod
+	def can_document_member(cls, member, membername, isattr, parent):
+		if type(member) is dict and member.get('environ') is os.environ:
+			return True
+		else:
+			return False
+
+	def import_object(self, *args, **kwargs):
+		ret = super(EnvironDocumenter, self).import_object(*args, **kwargs)
+		if not ret:
+			return ret
+		self.object = self.object.copy()
+		if 'home' in self.object:
+			self.object.update(home=Repr('home directory'))
+		self.object.update(environ=Repr('environ dictionary'))
+		return True
+
+
 def setup(app):
 	autodoc.setup(app)
 	app.add_autodocumenter(ThreadedDocumenter)
+	app.add_autodocumenter(EnvironDocumenter)