Features:

• allow using non-branch symbolic refs in a git source (#4845, @segiddins)
• allow absolute paths in the cache path setting (#5627, @mal)
• gems created via bundle gem with rspec have --require spec_helper in their .rspec file (@koic)
• bundle env includes Gem.ruby and the bundle binstub shebang when they don't match (#5616, @segiddins)
• allow passing gem names to bundle pristine (@segiddins)
• bundle version and bundle env include the commit and build date for the bundler gem (#5049, @segiddins)
• add the --shebang option to bundle binstubs (#4070, @segiddins, @Zorbash)
• gemfiles are evaled one fewer time when running bundle install (#4952, #3096, #4417, @segiddins)
• the fileutils gem is now vendored so different versions of the gem can be activated (@segiddins)
• speed up no-op installations (#5842, @segiddins)
• default to keeping the lockfile in the default gem template (@deivid-rodriguez)
• add a special bundler binstub that ensures the correct version of bundler is activated (#5876, @segiddins)
• speed up dependency resolution and ensure that all resolvable gemfiles can be installed (@segiddins, @greysteil)
• add a bundle list command that prints the gems in use (#4754, @colby-swandale)
• allow adding credentials to a gem source during deployment when allow_deployment_source_credential_changes is set (@adrian-gomez)
• making an outdated (and insecure) TLS connection to rubygems.org will print a warning (@segiddins)

Bugfixes:

• allow configuring a mirror fallback timeout without a trailing slash (#4830, @segiddins)
• fix handling of mirrors for file: urls that contain upper-case characters (@segiddins)
• list the correct gem host for rake release when allowed_push_host has been set (@mdeering)
• ensure Bundler.original_env preserves all env keys that bundler sets (#5700, @segiddins)
• ensure bundle pristine removes files added to a git gem (@segiddins)
• load plugin files from path gems before gem installation (#5429, @segiddins)
• ensure gems containing manpages are properly set up (#5730, @segiddins)
• avoid fetching remote specs when all effected gems are in groups that are not being installed (@segiddins)
• allow BUNDLE_GEMFILE to be a relative path (#5712, @gxespino)
• show a more helpful error message when a gem fails to install due to a corrupted lockfile (#5846, @segiddins)
• add a process lock to allow multiple concurrent bundle installs (#5851, @stefansedich)
• ensure that specifications always return an array for #extensions (@greysteil)
• print a helpful error message when using a gem in the Gemfile with an empty name (@colby-swandale)
• ensure that all gemfiles are included in bundle env (@segiddins)
• use ssl client cert and ca cert settings from gem configuration as fallbacks (@stan3)
• avoid global namespace pollution when loading gems (#5958, @shyouhei)
• avoid running a complete re-resolve on bundle update --bundler (@segiddins)
• allow bundle binstubs --standalone to work without path being set (@colby-swandale)
• fix support for bundle paths that include jars or wars on jruby (#5975, @torcido)