bug#58921: Tab completion hangs in eshell

[Gerd Möllmann]

reza <reza@housseini.me> writes:

> Open an eshell:
>
>      M-x eshell <enter>
>
> Type this command in the eshell
>
>      tab --warning=no-timestamp -xf <tab>
>
> emacs will hang and has to be killed.
>
> This behavior does not occur when only typing
>
>      tar -xf <tab>

Didn't check 28.  On master, it gets into a loop which can be
interrupted with C-g.  Backtrace is

Debugger entered--Lisp error: (quit)
  pcomplete-match("\\`--suffix=" 0)
  pcomplete/tar()
  pcomplete-completions()
  pcomplete-completions-at-point()
  completion--capf-wrapper(pcomplete-completions-at-point all)
  run-hook-wrapped(completion--capf-wrapper pcomplete-completions-at-point all)
  completion-at-point()
  funcall-interactively(completion-at-point)
  call-interactively(completion-at-point nil nil)
  command-execute(completion-at-point)

Maybe this helps someone knowing pcomplete.