Sort shortest files in each load paths

There are two directories where csv*/**/*.rb exist, lib/ and
test/, and depending on the order of tests, test/ may be placed
before lib/.  In that case, as "shortest" names were not sorted,
csv/helper.rb will be the first candidate for "csv".

Author: nobu

lib/irb/completion.rb

@@ -64,18 +64,22 @@ def self.retrieve_gem_and_system_load_path
     end
 
     def self.retrieve_files_to_require_from_load_path
-      @@files_from_load_path ||= retrieve_gem_and_system_load_path.map { |path|
-        begin
-          Dir.glob("**/*.{rb,#{RbConfig::CONFIG['DLEXT']}}", base: path)
-        rescue Errno::ENOENT
-          []
-        end
-      }.inject([]) { |result, names|
-        shortest, *rest = names.map{ |n| n.sub(/\.(rb|#{RbConfig::CONFIG['DLEXT']})\z/, '') }.sort
-        result.unshift(shortest) if shortest
-        result.concat(rest)
-        result
-      }.uniq
+      @@files_from_load_path ||=
+        (
+          shortest = []
+          rest = retrieve_gem_and_system_load_path.each_with_object([]) { |path, result|
+            begin
+              names = Dir.glob("**/*.{rb,#{RbConfig::CONFIG['DLEXT']}}", base: path)
+            rescue Errno::ENOENT
+              nil
+            end
+            next if names.empty?
+            names.map! { |n| n.sub(/\.(rb|#{RbConfig::CONFIG['DLEXT']})\z/, '') }.sort!
+            shortest << names.shift
+            result.concat(names)
+          }
+          shortest.sort! | rest
+        )
     end
 
     def self.retrieve_files_to_require_relative_from_current_dir