Fix Bundler that re-exec $0 when a version is present in the config:

[Edouard-chin]

Fix Bundler that re-exec $0 when a version is present in the config:

Problem

If you have a version in your config file (this feature was introduced in #6817), then running any bundle command will make Bundler re-exec and ultimately run the bundle binstub twice.

Details

When the bundle binstub gets executed, a require "bundler" is evaluated. RubyGems tries to require the bundler.rb file from the right bundler gem (in the event where you have multiple bundler versions in your system). RubyGems will prioritize a bundler version based on a few heurisitics.

rubygems/lib/rubygems/bundler_version_finder.rb

Lines 19 to 21 in b50c40c

	def self.prioritize!(specs)
	exact_match_index = specs.find_index {|spec| spec.version == bundler_version }
	return unless exact_match_index

This prioritize logic doesn't take into account the bundler version a user has specified in its config. So what happens is:

1. User execute the bundle binstub
2. require 'bundler' is evaluated.
3. RubyGems prioritize activating the bundler version specified in the Gemfile.lock
4. The CLI starts, and Auto switch kicks in. Bundler detects that user has a specific version in its config and the current runtime Bundler version doesn't match.
5. Bundler exit and re-exec with the right bundler version.

Solution

This patch introduce two fixes. First, it reads the bundler config file and check for the local config and then the global config. This is because the local has precedence over global (see the order here.

Second, the prioritization takes into account the version in a user's config and let RubyGems activate the right version in order to prevent re-exec moments later.

Finally, I also want to fix this problem because its a step toward fixing #8106. I'll open a follow up patch to explain.

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags