[ruby/reline] Suppress error in case INPUTRC env is empty

https://github.com/ruby/reline/commit/bce7e7562b

lib/reline/config.rb

@@ -83,8 +83,17 @@ class Reline::Config
     @key_actors[@keymap_label]
   end
 
+  def inputrc_path
+    case ENV['INPUTRC']
+    when nil, ''
+      DEFAULT_PATH
+    else
+      ENV['INPUTRC']
+    end
+  end
+
   def read(file = nil)
-    file ||= File.expand_path(ENV['INPUTRC'] || DEFAULT_PATH)
+    file ||= File.expand_path(inputrc_path)
     begin
       if file.respond_to?(:readlines)
         lines = file.readlines

test/reline/test_config.rb

@@ -206,4 +206,13 @@ class Reline::Config::Test < Reline::TestCase
     history << "a\n"
     assert_equal 1, history.size
   end
+
+  def test_empty_inputrc_env
+    inputrc_backup = ENV['INPUTRC']
+    ENV['INPUTRC'] = ''
+    assert_nothing_raised do
+      @config.read
+    end
+    ENV['INPUTRC'] = inputrc_backup
+  end
 end