Holidays with identical names in the same region are merged into the same entry

[brenauj]

Summary

---

Regions that have the same name for different days only have one entry for this name

Current behavior

---

For the bg_bg region the Възкресение Христово. Великден holiday has 2 entries in the YAML, but only one of them is returned by the gem.

~/gems/holidays$ make console
bundle exec rake console
irb -r rubygems -I lib -r holidays.rb
irb(main):001:0> Holidays::Factory::Definition.regions_repository.all_loaded
=> []
irb(main):002:0> Holidays.on(Date.civil(2020, 4, 6), :bg_bg)
=> [{:date=>#<Date: 2020-04-06 ((2458946j,0s,0n),+0s,2299161j)>, :name=>"Възкресение Христово. Великден", :regions=>[:bg_bg, :bg_bg]}]
irb(main):003:0> Holidays.on(Date.civil(2020, 4, 7), :bg_bg)
=> []
irb(main):004:0> Holidays::Factory::Definition.regions_repository.all_loaded
=> [:bg]
irb(main):005:0>

Expected behaviour

---

~/gems/holidays$ make console
bundle exec rake console
irb -r rubygems -I lib -r holidays.rb
irb(main):001:0> Holidays::Factory::Definition.regions_repository.all_loaded
=> []
irb(main):002:0> Holidays.on(Date.civil(2020, 4, 6), :bg_bg)
=> [{:date=>#<Date: 2020-04-06 ((2458946j,0s,0n),+0s,2299161j)>, :name=>"Възкресение Христово. Великден", :regions=>[:bg_bg]}]
irb(main):003:0> Holidays.on(Date.civil(2020, 4, 7), :bg_bg)
=> [{:date=>#<Date: 2020-04-07 ((2458947j,0s,0n),+0s,2299161j)>, :name=>"Възкресение Христово. Великден", :regions=>[:bg_bg]}]
irb(main):004:0> Holidays::Factory::Definition.regions_repository.all_loaded
=> [:bg]
irb(main):005:0>

Steps to reproduce

---

1. Have a region that has two holidays with the exact same name (bg_bg).
2. Have the holidays with the same function but not the same modifier.
3. Load holidays via make console.
4. Call Holidays with a date matching the first holiday. You should receive the target holiday with region duplicated in the regions array.
5. Call Holidays with a date matching the second holiday. You should receive an empty array.

Detailed description

---

This specific scenario was found by testing if Holidays.between yields the same dates on the same range for bg_en and bg_bg. A diff was found on Date.civil(2020, 4, 7) being returned for bg_en as Easter Monday but not for bg_bg.

For the bg_bg region the Възкресение Христово. Великден holiday has 2 entries in the YAML, but only one of them appears in the generated Ruby code.
From https://github.com/holidays/definitions/blob/v4.1.0/bg.yaml:

  - name: Easter Sunday
    regions: [bg_en]
    function: orthodox_easter_julian(year)
  - name: Възкресение Христово. Великден
    regions: [bg_bg]
    function: orthodox_easter_julian(year)
  - name: Easter Monday
    regions: [bg_en]
    function: orthodox_easter_julian(year)
    function_modifier: 1
  - name: Възкресение Христово. Великден
    regions: [bg_bg]
    function: orthodox_easter_julian(year)
    function_modifier: 1

May be related to #344.