`xsel` won't expand in one zsh but will in another

Question

Many days ago, the zsh of my Arch Linux did what I want: if I entered `xsel` and pressed Tab, it would be replaced by the output of xsel. Now, on the same box, I get this:

xsel: fstat error on stdin: Bad file descriptor

What's more strange, I have setup another Arch Linux now, with the same zsh and config files. It just does this expansion right.

I write a simple script a to discover what happens to the stdin:

#!/bin/zsh
echo $(readlink /proc/self/fd/0)

Let's try again---`./a`, and press Tab. On the former box, I get

pipe:\[4434444\]

and on the latter which is what I want:

/dev/pts/6

What should I do further to find out why they are different and get the expansion right?

Answer 1

I finally find out that this is caused by this zsh-history-substring-search script sosurced from my .zshrc when available. I still don't know why this happens, but I've opened an issue for this.