[rubygems/rubygems] Deprecate unused Bundler#SpecSet methods

ruby/rubygems@380c95ce05

Author: deivid-rodriguez

lib/bundler/spec_set.rb

@@ -179,6 +179,8 @@ def insecurely_materialized_specs
     end
 
     def -(other)
+      SharedHelpers.major_deprecation 2, "SpecSet#- has been removed with no replacement"
+
       SpecSet.new(to_a - other.to_a)
     end
 
@@ -210,6 +212,8 @@ def what_required(spec)
     end
 
     def <<(spec)
+      SharedHelpers.major_deprecation 2, "SpecSet#<< has been removed with no replacement"
+
       @specs << spec
     end