Copying a wrapped line results in a newline at the end of the wrapped line

[akalipetis]

Copying and pasting a wrapped line, introduces a newline character at the position the line was wrapped.

Steps to reproduce

1. Open the demo
2. Paste a long echo line, like the one below:

   echo this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big
   

3. When copied, the resulting line should be:

   this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big
   

4. It actually is:

   this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-
   is-big-this-is-big-this-is-big-this-is-big-this-is-big-this-is-big
   

[akalipetis]

For a real-world example, you can see play-with-docker/play-with-docker#66

[marcosnils]

@Tyriar do you think this is easy to fix?

[Tyriar]

@marcosnils not at the moment as this is blocked on #325, that change wwill properly track and re-wrap lines when resized, This should encode information for lines spanning multiple rows.

Once that is done though, ClipboardHandler here will just need to grab that line/row information and remove the problem new lines.

[cancan101]

Now that #325 is fixed, where does this issue stand (I am seeing it on: jupyter/notebook#2256)?

[Tyriar]

The PR for #325 only fixed a portion of the problem, this is now blocked on #622 which has a (big) PR out.