gem install pg --with-pg-config は動作するが、bundle は失敗する。

質問

(rootで)実行すると

gem install pg -v '0.12.0' -- --with-pg-config=/usr/pgsql-9.1/bin/pg_config

次のような出力が得られます。

#-> gem instal pg -v '0.12.0' -- --with-pg-config=/usr/pgsql-9.1/bin/pg_config
Building native extensions.  This could take a while...
Successfully installed pg-0.12.0
1 gem installed
Installing ri documentation for pg-0.12.0...
Installing RDoc documentation for pg-0.12.0...
#-> 

bundle installを実行すると。

Installing pg (0.12.0) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

    /usr/local/rvm/rubies/ruby-1.9.2-p290/bin/ruby extconf.rb 
checking for pg_config... no
No pg_config... trying anyway. If building fails, please try again with
--with-pg-config=/path/to/pg_config
checking for libpq-fe.h... no
Can't find the 'libpq-fe.h header
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
--with-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/usr/local/rvm/rubies/ruby-1.9.2-p290/bin/ruby
--with-pg
--without-pg
--with-pg-dir
--without-pg-dir
--with-pg-include
--without-pg-include=${pg-dir}/include
--with-pg-lib
--without-pg-lib=${pg-dir}/lib
--with-pg-config
--without-pg-config
--with-pg_config
--without-pg_config


Gem files will remain installed in /var/www/simpletrac/vendor/cache/ruby/1.9.1/gems/pg-    0.12.0 for inspection.
Results logged to /var/www/simpletrac/vendor/cache/ruby/1.9.1/gems/pg-0.12.0/ext/gem_make.out
An error occured while installing pg (0.12.0), and Bundler cannot continue.
Make sure that `gem install pg -v '0.12.0'` succeeds before bundling.

libpq-fe.h が /usr/pgsql-9.1/include/libpq-fe.h にインストールされているので、試してみました。

gem install pg -v '0.12.0' -- --with-pg-config=/usr/pgsql-9.1/bin/pg_config --with-pg-lib=/usr/pgsql-9.1/include/libpq-fe.h but still no go. 

何かお手伝いいただけることがあれば、ぜひお願いします。

また、postgresql91-develとruby-develはインストール済みです。 CentOS 6 を実行しています。

どのように解決するのですか？

を実行する前に、これを実行してみましたか？ bundle install ?

bundle config build.pg --with-pg-config=/usr/pgsql-9.1/bin/pg_config

参照 http://bundler.io/v1.3/bundle_config.html