Merge RubyGems 2.7.7

see release details here: https://blog.rubygems.org/2018/05/18/2.7.7-released.html

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63461 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/rubygems.rb

@@ -10,7 +10,7 @@ require 'rbconfig'
 require 'thread'
 
 module Gem
-  VERSION = "2.7.6"
+  VERSION = "2.7.7"
 end
 
 # Must be first since it unloads the prelude from 1.9.2
@@ -604,7 +604,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
 
   private_class_method :find_home
 
-  # FIXME deprecate these in 3.0
+  # TODO:  remove in RubyGems 4.0
 
   ##
   # Zlib::GzipReader wrapper that unzips +data+.
@@ -613,6 +613,11 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     Gem::Util.gunzip data
   end
 
+  class << self
+    extend Gem::Deprecate
+    deprecate :gunzip, "Gem::Util.gunzip", 2018, 12
+  end
+
   ##
   # Zlib::GzipWriter wrapper that zips +data+.
 
@@ -620,6 +625,11 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     Gem::Util.gzip data
   end
 
+  class << self
+    extend Gem::Deprecate
+    deprecate :gzip, "Gem::Util.gzip", 2018, 12
+  end
+
   ##
   # A Zlib::Inflate#inflate wrapper
 
@@ -627,6 +637,11 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
     Gem::Util.inflate data
   end
 
+  class << self
+    extend Gem::Deprecate
+    deprecate :inflate, "Gem::Util.inflate", 2018, 12
+  end
+
   ##
   # Top level install helper method. Allows you to install gems interactively:
   #
@@ -1225,9 +1240,12 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
 
   class << self
     ##
-    # TODO remove with RubyGems 3.0
+    # TODO remove with RubyGems 4.0
 
     alias detect_gemdeps use_gemdeps # :nodoc:
+
+    extend Gem::Deprecate
+    deprecate :detect_gemdeps, "Gem.use_gemdeps", 2018, 12
   end
 
   # FIX: Almost everywhere else we use the `def self.` way of defining class