reverse-i-search not work fine when mapping jj to ESC in vi mode

[Clark J. Wang]

Try like this:

[bash-4.2.8] # set -o vi
[bash-4.2.8] # bind -m vi-insert '"jj": "\e"'
[bash-4.2.8] # echo jk
[bash-4.2.8] # echo k
[bash-4.2.8] #

Then press ctrl-r and enter jk to search. It'll find ``echo k'' instead of
``echo jk''. Bug?