Ensure no escape sequence before printing prompt

lib/reline/io/ansi.rb

@@ -242,7 +242,7 @@ def set_screen_size(rows, columns)
   end
 
   def cursor_pos
-    if @input.tty? && @output.tty?
+    if both_tty?
       res = +''
       m = nil
       @input.raw do |stdin|
@@ -276,6 +276,10 @@ def cursor_pos
     Reline::CursorPos.new(column, row)
   end
 
+  def both_tty?
+    @input.tty? && @output.tty?
+  end
+
   def move_cursor_column(x)
     @output.write "\e[#{x + 1}G"
   end
@@ -343,14 +347,14 @@ def set_winch_handler(&handler)
 
   def prep
     # Enable bracketed paste
-    @output.write "\e[?2004h" if Reline.core.config.enable_bracketed_paste
+    @output.write "\e[?2004h" if Reline.core.config.enable_bracketed_paste && both_tty?
     retrieve_keybuffer
     nil
   end
 
   def deprep(otio)
     # Disable bracketed paste
-    @output.write "\e[?2004l" if Reline.core.config.enable_bracketed_paste
+    @output.write "\e[?2004l" if Reline.core.config.enable_bracketed_paste && both_tty?
     Signal.trap('WINCH', @old_winch_handler) if @old_winch_handler
   end
 end

test/reline/test_reline.rb

@@ -378,6 +378,17 @@ def test_dumb_terminal
     assert_match(/#<Reline::Dumb/, out.chomp)
   end
 
+  def test_print_prompt_before_everything_else
+    lib = File.expand_path("../../lib", __dir__)
+    code = "p Reline::IOGate.class; p Reline.readline 'prompt> '"
+    out = IO.popen([Reline.test_rubybin, "-I#{lib}", "-rreline", "-e", code], "r+") do |io|
+      io.write "abc\n"
+      io.close_write
+      io.read
+    end
+    assert_match(/\AReline::ANSI\nprompt> /, out)
+  end
+
   def test_require_reline_should_not_trigger_winsize
     pend if win?
     lib = File.expand_path("../../lib", __dir__)