On Dec 6, 2016 6:58 PM, "Zhiming Wang" <zmwangx@gmail.com> wrote:

Commit 20948d0 (38579: Functions/Zle/bracketed-paste-magic: simplify saving
and
restoring of state) introduced a regression that results in the ZLE buffer
being repeated when pasting under certain conditions.

[...]

Here's a simple reproducer:

2. Press the following sequence of keys (no space): ^R echo ^R ^E
   (history-incremental-search-backward, "echo",
   history-incremental-search-backward, end-of-line), then paste something,
   say, "zsh".


This probably indicates a problem with undo-point handling around history
search, which has been a sticky wicket in the past.  The patch you cite
replaced b-p-m's internal handling of $BUFFER with reliance on the undo
mechanism.

 For the 5.3 release the easiest approach is likely to be to back out that
change and re-apply it after the release when it can be more thoroughly
debugged.