Don't print useless prompt before escape sequence

[tompng]

Fixes #833

Reline used to print prompt in nomultiline mode before printing any escape sequence because readline-ext's test was requiring.
It's completely useless because printed prompt will be cleared immediately.
This behavior causes line-wrapped long prompt displayed twice.

Before:

Reline.readline 'prompt'+'>'*50
prompt>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
prompt>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>> Prompt displayed twice

After:

Reline.readline 'prompt'+'>'*50
prompt>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>> OK

Side effect

Test code that depend on this behavior needs to be modified.

• rubygems/rubygems: two test fails
  • bundler/spec/commands/info_spec.rb
  • bundler/spec/commands/show_spec.rb
• ruby/debug
  • console_test seems to pass
• ruby/rdoc
  • ri test seems to pass

[deivid-rodriguez]

Thank you for fixing this!

I did find that line as suspicious and tried removing it, but saw one failing test and decided to not dig further and report the problem instead 😅

I'll gladly update Bundler specs to match correct behavior 👍.

[ima1zumi]

LGTM!