[Tcsh] "history-search-backward" weirdness

[Jamie Landeg-Jones]

When using "history-search-backward", it will scroll up through all matches
ih the history, doing nothing if there is no match, or no further match.

However, if the first character of the current line is '[' then whilst it
correctly searches through the history for commands starting with '[', it
bombs out if there is no match / no further match (as long as there is at
least one entry in the history):

%  bindkey -k up history-search-backward
% pwd
/home/jamie

Typing '[' followed by UP ARROW gives:

% [history: Missing ']'
% <CURSOR>

% [ 3 ] && echo boo
boo

Now, typing '[' followed by UP ARROW gives correctly:

% [ 3 ] && echo boo<CURSOR>

Pressing UP ARROW again changes it to:

% [ 3 ] && echo booecho: Missing ']'.
% <CURSOR>

Any ideas what is going on? Tested on latest version of tcsh, on both FreeBSD and Linux.

Cheers! Jamie