Log Message:
Update ruby-bundler to 1.2.3.

## 1.2.3 (Nov 29, 2012)

Bugfixes:

  - fix exceptions while loading some gemspecs

## 1.2.2 (Nov 14, 2012)

Bugfixes:

  - support new Psych::SyntaxError for Ruby 2.0.0 (@tenderlove, @sol)
  - `bundle viz` works with git gems again (@hirochachacha)
  - recognize more cases when OpenSSL is not present

## 1.2.1 (Sep 19, 2012)

Bugfixes:

  - `bundle clean` now works with BUNDLE_WITHOUT groups again
  - have a net/http read timeout around the Gemcutter API Endpoint