Pasted entities get converted to text that can bypass escaping

I discovered this while testing CONF-10166

Copy the following text from this issue and paste it into the rich text editor

(?)

Then switch to wiki markup.
The wikimarkup will just display

(?)

instead of escaping it with a backslash.

However, if you copy it from other places, such as a command line, or type it in, then it will be correctly escaped.

I assume that the paste is converting some of the characters to html entities, and that when the converter tries to do its emoticon escaping the patterns fail due to those entities.