[rubygems/rubygems] Remove all `syck` traces from `rubygems`

After reading [this blog
post](https://blog.rubygems.org/2011/08/31/shaving-the-yaml-yak.html),
published almost 10 years ago already, my understanding is that this
problem could come up in two ways:

* Rubygems.org serving corrupted gemspecs". As far as I understand this
was fixed in rubygems.org a lot time ago, since
https://github.com/rubygems/rubygems.org/pull/331.

* Clients having a ten years old gemspec cache with some of these bad
gemspecs. In this case, there's no easy solution but I think ten years
is enough and rebuilding the cache should do the trick.

So, I think it's time we remove this.

https://github.com/rubygems/rubygems/commit/afcb15d556

1 files changed, 0 insertions, 10 deletions

diff --git a/lib/rubygems.rb b/lib/rubygems.rb
index 1c5a25fd7f..60a599e380 100644
--- a/lib/rubygems.rb
+++ b/lib/rubygems.rb
@@ -628,12 +628,6 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     rescue ::LoadError
       # If we can't load psych, that's fine, go on.
     else
-      # If 'yaml' has already been required, then we have to
-      # be sure to switch it over to the newly loaded psych.
-      if defined?(YAML::ENGINE) && YAML::ENGINE.yamler != "psych"
-        YAML::ENGINE.yamler = "psych"
-      end
-
       require 'rubygems/psych_additions'
       require 'rubygems/psych_tree'
     end
@@ -641,10 +635,6 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     require 'yaml'
     require 'rubygems/safe_yaml'
 
-    # Now that we're sure some kind of yaml library is loaded, pull
-    # in our hack to deal with Syck's DefaultKey ugliness.
-    require 'rubygems/syck_hack'
-
     @yaml_loaded = true
   end