Auto merge of #5933 - NickLaMuro:bundle-pristine-respect-bundler-config, r=segiddins

Use Bundler::Installer for bundle pristine

Fixes bundler pristine to respect the `bundle config` options for particular gems.  In my particular case, on OSX I have a keg version of `pg` and a bundle config with the following entry:

```console
$ bundle config
...

build.pg
Set for the current user (/Users/nicklamuro/.bundle/config): "--with-pg-config=/usr/local/Cellar/postgresql@9.5/9.5.6/bin/pg_config"

```

This would not be respected

What was the end-user problem that led to this PR?
--------------------------------------------------

See above, but steps to reproduce (requires `bundler` >= 1.15):

1. Install postgres on your machine if it is not already there (OS dependent)

2. Add the following bundler build arg for `pg`:

  ```console
  $ bundle config build.pg -- --with-pg-config=$(which pg_config)
  ```

2. Make sure `pg_config` is not in your `$PATH`:

  ```console
  $ export PATH=$(echo "$PATH" | sed "s|:$(dirname $(which pg_conf)))||")
  ```

* Create a simple project with `pg` as a single gem in your Gemfile:

  ```
  # Gemfile
  gem "pg"
  ```

* Bundle:

  ```console
  $ bundle install
  ```

* Attempt to `bundle pristine` (you should get an error):

  ```console
  $ bundle pristine
  ```

What was your diagnosis of the problem?
---------------------------------------

The newly added `bundle pristine` did no use the same code that was used by `bundle install` to execute the re-installation of the gem.

What is your fix for the problem, implemented in this PR?
---------------------------------------------------------

By making use of the `Bundler::Installer` and `Bundler::Installer::GemInstaller` code that is already used with `bundle install`, we can reuse the code that injects the `bundle config` options into each gem that is being installed.

Why did you choose this fix out of the possible options?
--------------------------------------------------------

Didn't want to repeat code that was already being used elsewhere.  Caused a few lines of code to be added that weren't there previously, but nothing obscene.

(cherry picked from commit da6a52a9b255147b389d29e2b22ce397bbb8377b)

# Conflicts:
#	lib/bundler/cli/pristine.rb
#	spec/commands/pristine_spec.rb

1 files changed, 10 insertions, 7 deletions

diff --git a/lib/bundler/cli/pristine.rb b/lib/bundler/cli/pristine.rb
index 30542b583e..10d03b4b41 100644
--- a/lib/bundler/cli/pristine.rb
+++ b/lib/bundler/cli/pristine.rb
@@ -4,29 +4,32 @@ require "bundler/cli/common"
 module Bundler
   class CLI::Pristine
     def run
+      definition = Bundler.definition
+      definition.validate_runtime!
+      installer = Bundler::Installer.new(Bundler.root, definition)
+
       Bundler.load.specs.each do |spec|
         next if spec.name == "bundler" # Source::Rubygems doesn't install bundler
 
         gem_name = "#{spec.name} (#{spec.version}#{spec.git_version})"
         gem_name += " (#{spec.platform})" if !spec.platform.nil? && spec.platform != Gem::Platform::RUBY
 
-        case spec.source
+        case source = spec.source
         when Source::Rubygems
           cached_gem = spec.cache_file
           unless File.exist?(cached_gem)
             Bundler.ui.error("Failed to pristine #{gem_name}. Cached gem #{cached_gem} does not exist.")
             next
           end
-
-          FileUtils.rm_rf spec.full_gem_path
-          spec.source.install(spec, :force => true)
         when Source::Git
-          git_source = spec.source
-          git_source.remote!
-          git_source.install(spec, :force => true)
+          source.remote!
         else
           Bundler.ui.warn("Cannot pristine #{gem_name}. Gem is sourced from local path.")
+          next
         end
+        FileUtils.rm_rf spec.full_gem_path
+
+        Bundler::GemInstaller.new(spec, installer, false, 0, true).install_from_spec
       end
     end
   end