_fzf_complete_*() not handling prompt color codes correctly

- [x] I have read through the manual page (`man fzf`)
- [x] I have the latest version of fzf
- [x] I have searched through the existing issues

## Info

- OS
- [x] Linux
- [ ] Mac OS X
- [ ] Windows
- [ ] Etc.
- Shell
- [ ] bash
- [x] zsh
- [ ] fish

## Problem / Steps to reproduce

doing:
~ export **
returns this to the command line:
[green]~[blue] export ...

The literal characters [green] and [blue] not the color codes.

Running oh-my-zsh with simple theme.