Promote abbrev to default gems

doc/maintainers.rdoc

@@ -38,8 +38,6 @@ Zachary Scott (zzak)
 
 === Libraries
 
-[lib/abbrev.rb]
-  Akinori MUSHA (knu)
 [lib/base64.rb]
   Yusuke Endoh (mame)
 [lib/drb.rb, lib/drb/*]
@@ -106,6 +104,9 @@ Zachary Scott (zzak)
 
 === Libraries
 
+[lib/abbrev.rb]
+  Akinori MUSHA (knu)
+  https://github.com/ruby/abbrev
 [lib/benchmark.rb]
   _unmaintained_
   https://github.com/ruby/benchmark

doc/standard_library.rdoc

@@ -8,7 +8,6 @@ description.
 
 == Libraries
 
-Abbrev:: Calculates a set of unique abbreviations for a given set of strings
 Base64:: Support for encoding and decoding binary data using a Base64 representation
 DEBUGGER__:: Debugging functionality for Ruby
 DRb:: Distributed object system for Ruby
@@ -42,6 +41,7 @@ WIN32OLE:: Provides an interface for OLE Automation in Ruby
 
 == Libraries
 
+Abbrev:: Calculates a set of unique abbreviations for a given set of strings
 Benchmark:: Provides methods to measure and report the time used to execute code
 Bundler:: Manage your Ruby application's gem dependencies
 CGI:: Support for the Common Gateway Interface protocol

lib/abbrev.gemspec

@@ -0,0 +1,22 @@
+Gem::Specification.new do |spec|
+  spec.name          = "abbrev"
+  spec.version       = "0.1.0"
+  spec.authors       = ["Akinori MUSHA"]
+  spec.email         = ["knu@idaemons.org"]
+
+  spec.summary       = %q{Calculates a set of unique abbreviations for a given set of strings}
+  spec.description   = %q{Calculates a set of unique abbreviations for a given set of strings}
+  spec.homepage      = "https://github.com/ruby/abbrev"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  spec.files         = Dir.chdir(File.expand_path('..', __FILE__)) do
+    `git ls-files -z`.split("\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
+  end
+  spec.bindir        = "exe"
+  spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
+  spec.require_paths = ["lib"]
+end

tool/sync_default_gems.rb

@@ -68,6 +68,7 @@ REPOSITORIES = {
   erb: "ruby/erb",
   nkf: "ruby/nkf",
   tsort: "ruby/tsort",
+  abbrev: "ruby/abbrev",
 }
 
 def sync_default_gems(gem)