Problem

Plugins with the rev indicator get an error on update:

You are not currently on a branch. Please specify which branch you want to merge with. See git-pull(1) for details.^@^@ git pull

The reason is that plugins with rev are being checked-out as "detached" branches which are read-only, git-pull is not permitted on a detached branch.

Expect

I would expect to see no errors when updating my plugins.

Reproduce

Minimal .vimrc:

if has('vim_starting')
  set nocompatible
  set runtimepath+=~/.vim/bundle/neobundle.vim/
endif

call neobundle#begin(expand('~/.vim/bundle'))
NeoBundleFetch 'Shougo/neobundle.vim'
NeoBundle 'pangloss/vim-javascript.git', { 'rev': '51a337b' }
NeoBundle 'groenewege/vim-less.git', { 'rev': '5d965c2' }
call neobundle#end()

filetype plugin indent on
NeoBundleCheck

1. Open vim and let NeoBundle install plugins.
2. Run :NeoBundleUpdate! (force) to update plugins.
3. Run :message.

Notice the errors for plugins with the rev indicator.

Ideas

I can think of some solutions:

Option A: Use real branch

When a plugin has a rev, do not detach, checkout with a real branch e.g. git checkout -b rev 63f0392

Option B: Check current revision

Before pulling, if (a) plugin has rev AND (b) already cloned, verify current revision and cancel pulling if current revision == rev indicator.

Option C: Checkout master

Before pulling, if (a) plugin has rev, AND (b) already cloned, checkout the local branch master. (git checkout master)

Hope this helps..