FF/Chrome: Paragraphs go nuts after modifying copy-pasted text

[Jude Allred]

This bug was discovered as a user attempted to manipulate some copy-pasted song lyrics. Here's an excerpt of the source that was generated by the paste:

<p>
    Big wheels keep on turning,<br />
    carry me home to see my kin<br />
    singing songs about the southland.<br />
    I miss ole bamy once again and I think it&#39;s a sin.<br />
    Well, I heard Mister Young sing about her.<br />
    Well, I heard ole Neil put her down.<br /></p> 

Steps:

1. go to ckeditor.com/demo
2. set the source to the code snippet above
3. return to wysiwyg mode

now...

In Firefox:

1. Go to the end of the Nth line (where N > 1)
2. Hit Enter
3. Hit Backspace
4. Hit Shift + Enter
5. [Bug] Watch first line disappear and cursor jump to top

In Chrome:

1. Go to the end of the Nth line (where N > 1)
2. Hit Enter
3. Hit Backspace
4. Hit Shift + Enter
5. You are now unable to get rid of your newly created paragraphs

[Krzysztof Studnik]

Confirmed in Chrome 7 since CKE 3.0 and Under Firefox 3.6.10 CKE 3.0 - shift+enter - no response CKE 3.2 - an error occured once in firebug console

w.getFirst() is null
[Break on this error] while(u=l.call(this,t))v=u;return v;};...w.append(t.document.createText('')); 
CKE 3.4.1 and .4.2 - confirmed

[Krzysztof Studnik]

Correction krst: Confirmed in Chrome 7 since CKE 3.0
and
Under Firefox 3.6.10

• CKE 3.0 - shift+enter - no response
• CKE 3.2 - an error occured once in firebug console

   w.getFirst() is null
   [Break on this error] while(u=l.call(this,t))v=u;return v;};...w.append(t.document.createText('')); 
  

• CKE 3.4.1 and .4.2 - confirmed

[Jakub Ś]

I have checked this behaviour in CKEditor 4.2.1.

In Firefox step 4 doesn't create new line, cursor is moved to next line only.

In Blink and Webkit: Text gets split in two and it is impossible to join two paragraphs again.

No JS errors are thrown.