Fixed https://github.com/amix/vimrc/issues/546

This is done by removing custom FileType indent options, and using
`vim-python-pep8-indent` plugin.

sources_non_forked/vim-python-pep8-indent/spec/vimrc

@@ -0,0 +1,22 @@
+" vint: -ProhibitSetNoCompatible
+set nocompatible
+
+filetype plugin on
+filetype indent on
+syntax on
+
+set noswapfile nobackup
+
+" remove default ~/.vim directories to avoid loading plugins
+set runtimepath-=~/.vim
+set runtimepath-=~/.vim/after
+
+let sfile = expand('<sfile>')
+let plugin_path = fnamemodify(sfile, ':p:h:h')
+exe 'set runtimepath^='.plugin_path
+
+if !empty($PYTHON_PEP8_INDENT_TEST_PROFILE_BASE)
+  execute printf('profile start %s.%s',
+        \ $PYTHON_PEP8_INDENT_TEST_PROFILE_BASE, getpid())
+  execute 'profile! file '. plugin_path . '/indent/python.vim'
+endif