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/indent/bytes_spec.rb

@@ -0,0 +1,36 @@
+require "spec_helper"
+
+describe "handles byte strings" do
+  before(:all) {
+      vim.command 'syn region pythonBytes start=+[bB]"+ skip=+\\\\\|\\"\|\\$+ excludenl end=+"+ end=+$+ keepend contains=pythonBytesError,pythonBytesContent,@Spell'
+      vim.command "syn match pythonBytesEscape       '\\\\$'"
+  }
+
+  before(:each) {
+    # clear buffer
+    vim.normal 'gg"_dG'
+
+    # Insert two blank lines.
+    # The first line is a corner case in this plugin that would shadow the
+    # correct behaviour of other tests. Thus we explicitly jump to the first
+    # line when we require so.
+    vim.feedkeys 'i\<CR>\<CR>\<ESC>'
+  }
+
+  it "it does not indent to bracket in byte string" do
+    vim.feedkeys 'ireg = b"["\<Esc>'
+    vim.echo('map(synstack(line("."), col(".")), "synIDattr(v:val, \"name\")")'
+            ).should == "['pythonBytes']"
+    vim.feedkeys 'o'
+    indent.should == 0
+  end
+
+  it "it indents backslash continuation correctly" do
+    vim.feedkeys 'iwith foo, \<Bslash>\<Esc>'
+    vim.echo('getline(".")').should == "with foo, \\"
+    vim.echo('map(synstack(line("."), col(".")), "synIDattr(v:val, \"name\")")'
+            ).should == "['pythonBytesEscape']"
+    vim.feedkeys 'o'
+    indent.should == 8
+  end
+end