Bug: [ "(" = ")" ] is true

[Martijn Dekker <martijn@xxxxxxxx>]

There is a string comparison bug with `[' and `test'; the result is true
if the first string starts with '(' and the second string starts with ')'.

$ [ "(" = ")" ] && echo oops || echo ok
oops
$ [ ")" = "(" ] && echo oops || echo ok
ok
$ [ "((" = "))" ] && echo oops || echo ok
oops
$ [ "((" = ")x" ] && echo oops || echo ok
oops
$ [ "(x" = ")" ] && echo oops || echo ok
oops
$ [ "x(" = ")" ] && echo oops || echo ok
ok
$ [ "(" = "x)" ] && echo oops || echo ok
ok

This appears to be a long-standing bug. I confirmed it in:

zsh 4.3.6
zsh 5.1.1
zsh 5.2

I also found that the bug does *not* exist in zsh 4.1.1.

Also, `[[' does not have this problem.

Credit to /u/tilkau on reddit for discovering this bug:
https://www.reddit.com/r/bash/comments/3w1hm4/how_to_compare_values_to_literal/cxsknzh

Thanks,

- Martijn