util/rubocop -A --only Performance/Casecmp

lib/rubygems/commands/sources_command.rb

@@ -82,8 +82,8 @@ Do you want to add this source?
   def check_rubygems_https(source_uri) # :nodoc:
     uri = URI source_uri
 
-    if uri.scheme && uri.scheme.downcase == "http" &&
-       uri.host.downcase == "rubygems.org"
+    if uri.scheme && uri.scheme.casecmp("http").zero? &&
+       uri.host.casecmp("rubygems.org").zero?
       question = <<-QUESTION.chomp
 https://rubygems.org is recommended for security over #{uri}
 

lib/rubygems/remote_fetcher.rb

@@ -320,7 +320,7 @@ class Gem::RemoteFetcher
   end
 
   def https?(uri)
-    uri.scheme.downcase == "https"
+    uri.scheme.casecmp("https").zero?
   end
 
   def close_all

lib/rubygems/request/connection_pools.rb

@@ -45,7 +45,7 @@ class Gem::Request::ConnectionPools # :nodoc:
   end
 
   def https?(uri)
-    uri.scheme.downcase == "https"
+    uri.scheme.casecmp("https").zero?
   end
 
   def no_proxy?(host, env_no_proxy)