Allow manifest.js to be placed anywhere.

[yubele]

Description

This implementation ensures that you don't get an error if you place manifest.js anywhere (other than app/assets/config/manifest.js).

This fix may also help resolve #369.

Problems to fix

After moving manifest.js, I get a ManifestNeededError.

[yubele]

In the test below, it is failed, but I ran it in the same procedure as travis, but it did not reproduce in my environment.

https://travis-ci.org/github/rails/sprockets-rails/jobs/728618169
https://travis-ci.org/github/rails/sprockets-rails/jobs/728618185

log

yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ rvm use 2.5.8 --install --binary --fuzzy
Required ruby-2.5.8 is not installed - installing.
Searching for binary rubies, this might take some time.
Found remote file https://rvm_io.global.ssl.fastly.net/binaries/ubuntu/18.04/x86_64/ruby-2.5.8.tar.bz2
Checking requirements for ubuntu.
Requirements installation successful.
ruby-2.5.8 - #configure
ruby-2.5.8 - #download
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 19.0M  100 19.0M    0     0  20.8M      0 --:--:-- --:--:-- --:--:-- 20.7M
No checksum for downloaded archive, recording checksum in user configuration.
ruby-2.5.8 - #validate archive
ruby-2.5.8 - #extract
ruby-2.5.8 - #validate binary
ruby-2.5.8 - #setup
ruby-2.5.8 - #gemset created /home/ubuntu/.rvm/gems/ruby-2.5.8@global
ruby-2.5.8 - #importing gemset /home/ubuntu/.rvm/gemsets/global.gems..................................
ruby-2.5.8 - #generating global wrappers.......
ruby-2.5.8 - #gemset created /home/ubuntu/.rvm/gems/ruby-2.5.8
ruby-2.5.8 - #importing gemsetfile /home/ubuntu/.rvm/gemsets/default.gems evaluated to empty gem list
ruby-2.5.8 - #generating default wrappers.......
Using /home/ubuntu/.rvm/gems/ruby-2.5.8
yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ gem install bundler -v '<2'
Fetching bundler-1.17.3.gem
Successfully installed bundler-1.17.3
Parsing documentation for bundler-1.17.3
Installing ri documentation for bundler-1.17.3
Done installing documentation for bundler after 4 seconds
1 gem installed
yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ ls gemfiles/Gemfile.rails-^C
yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ export BUNDLE_GEMFILE=$PWD/gemfiles/Gemfile.rails-5.0.x.sprockets-4.x
yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ ruby --version
ruby 2.5.8p224 (2020-03-31 revision 67882) [x86_64-linux]
yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ gem install bundler -v '<2'
Successfully installed bundler-1.17.3
Parsing documentation for bundler-1.17.3
Done installing documentation for bundler after 3 seconds
1 gem installed
yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ bundle install --jobs=3 --retry=3 --path=${BUNDLE_PATH:-vendor/bundle}
Fetching https://github.com/rails/sprockets.git
Fetching gem metadata from https://rubygems.org/.............
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Fetching rake 13.0.1
Installing rake 13.0.1
Fetching concurrent-ruby 1.1.7
Fetching minitest 5.10.3
Installing minitest 5.10.3
Fetching thread_safe 0.3.6
Installing concurrent-ruby 1.1.7
Installing thread_safe 0.3.6
Fetching builder 3.2.4
Fetching erubis 2.7.0
Installing builder 3.2.4
Fetching mini_portile2 2.4.0
Installing erubis 2.7.0
Installing mini_portile2 2.4.0
Fetching crass 1.0.6
Installing crass 1.0.6
Fetching rack 2.2.3
Installing rack 2.2.3
Using bundler 1.17.3
Fetching execjs 2.7.0
Fetching ffi 1.13.1
Installing execjs 2.7.0
Fetching method_source 1.0.0
Installing method_source 1.0.0
Fetching thor 1.0.1
Installing ffi 1.13.1 with native extensions
Installing thor 1.0.1
Fetching rb-fsevent 0.10.4
Installing rb-fsevent 0.10.4
Fetching tzinfo 1.2.7
Installing tzinfo 1.2.7
Fetching i18n 1.8.5
Installing i18n 1.8.5
Fetching nokogiri 1.10.10
Installing nokogiri 1.10.10 with native extensions
Fetching rack-test 0.6.3
Installing rack-test 0.6.3
Using sprockets 4.0.2 from https://github.com/rails/sprockets.git (at master@dba2802)
Fetching uglifier 4.2.0
Fetching activesupport 5.0.7.2
Installing uglifier 4.2.0
Fetching rb-inotify 0.10.1
Installing activesupport 5.0.7.2
Installing rb-inotify 0.10.1
Fetching loofah 2.7.0
Installing loofah 2.7.0
Fetching sass-listen 4.0.0
Fetching rails-html-sanitizer 1.3.0
Installing sass-listen 4.0.0
Fetching rails-dom-testing 2.0.3
Installing rails-html-sanitizer 1.3.0
Fetching sass 3.7.4
Installing rails-dom-testing 2.0.3
Fetching actionview 5.0.7.2
Installing sass 3.7.4
Installing actionview 5.0.7.2
Fetching actionpack 5.0.7.2
Installing actionpack 5.0.7.2
Using sprockets-rails 3.2.2 from source at `..`
Fetching railties 5.0.7.2
Installing railties 5.0.7.2
Bundle complete! 8 Gemfile dependencies, 32 gems now installed.
Bundled gems are installed into `./gemfiles/vendor/bundle`
Post-install message from i18n:

HEADS UP! i18n 1.1 changed fallbacks to exclude default locale.
But that may break your application.

If you are upgrading your Rails application from an older version of Rails:

Please check your Rails app for 'config.i18n.fallbacks = true'.
If you're using I18n (>= 1.1.0) and Rails (< 5.2.2), this should be
'config.i18n.fallbacks = [I18n.default_locale]'.
If not, fallbacks will be broken in your app by I18n 1.1.x.

If you are starting a NEW Rails application, you can ignore this notice.

For more info see:
https://github.com/svenfuchs/i18n/releases/tag/v1.1.0

Post-install message from sass:

Ruby Sass has reached end-of-life and should no longer be used.

* If you use Sass as a command-line tool, we recommend using Dart Sass, the new
  primary implementation: https://sass-lang.com/install

* If you use Sass as a plug-in for a Ruby web framework, we recommend using the
  sassc gem: https://github.com/sass/sassc-ruby#readme

* For more details, please refer to the Sass blog:
  https://sass-lang.com/blog/posts/7828841

yusuke:~/environment/sprockets-rails (feature/support_any_manifest_location) $ bundle exec rake
/home/ubuntu/.rvm/rubies/ruby-2.5.8/bin/ruby -w -I"lib:lib" -I"/home/ubuntu/environment/sprockets-rails/gemfiles/vendor/bundle/ruby/2.5.0/gems/rake-13.0.1/lib" "/home/ubuntu/environment/sprockets-rails/gemfiles/vendor/bundle/ruby/2.5.0/gems/rake-13.0.1/lib/rake/rake_test_loader.rb" "test/test_helper.rb" "test/test_quiet_assets.rb" "test/test_railtie.rb" "test/test_task.rb" 
/home/ubuntu/environment/sprockets-rails/gemfiles/vendor/bundle/ruby/2.5.0/gems/activesupport-5.0.7.2/lib/active_support/core_ext/hash/slice.rb:21: warning: method redefined; discarding old slice
/home/ubuntu/environment/sprockets-rails/gemfiles/vendor/bundle/ruby/2.5.0/gems/actionview-5.0.7.2/lib/action_view/helpers/controller_helper.rb:14: warning: `*' interpreted as argument prefix
Run options: --seed 39417

# Running:

........................................................................................................................................................

Finished in 11.806762s, 12.8740 runs/s, 65.2169 assertions/s.