bug#72004: 30.0.50, master: 'erc--check-prompt-input-for-multiline-blanks' test fail

[Andrea Corallo <acorallo@gnu.org>]

Since few days I see 'erc--check-prompt-input-for-multiline-blanks'
failing.  I think the fail is intermittent and because of that I could
not determine the commit that introduced it.

I observe this both on emacs-30 both on master, the first commit in
emacs-30 where I observed it is 2fb6a98ecfa1579273a640e923f2e52f75e1f7ad
which seems unrelated (but I mention it so we have a point in time).

This is the output I see:

Test erc--check-prompt-input-for-multiline-blanks backtrace:
  user-error("Process not running")
  erc--run-input-validation-checks(#s(erc--input-split :string "a" :in
  run-hook-with-args(erc--run-input-validation-checks #s(erc--input-sp
  erc-send-current-line()
  #f(compiled-function (next) #<bytecode 0x1eab02298fb35043>)(#f(lambd
  funcall(#f(compiled-function (next) #<bytecode 0x1eab02298fb35043>)
  (progn (fset 'erc-server-buffer vnew) (fset 'erc-process-input-line
  (unwind-protect (progn (fset 'erc-server-buffer vnew) (fset 'erc-pro
  (let* ((vnew #'(lambda (&rest r) (setq calls (cons r calls)))) (vnew
  (let* ((erc--input-review-functions (remove 'erc-add-to-input-ring e
  (save-current-buffer (set-buffer (get-buffer-create "FakeNet")) (let
  erc-tests-common-with-process-input-spy(#f(compiled-function (next)
  #f(compiled-function () #<bytecode -0xaf493cb21b42d4b>)()
  #f(compiled-function () #<bytecode -0x1a6c2873f655e48c>)()
  handler-bind-1(#f(compiled-function () #<bytecode -0x1a6c2873f655e48
  ert--run-test-internal(#s(ert--test-execution-info :test #s(ert-test
  ert-run-test(#s(ert-test :name erc--check-prompt-input-for-multiline
  ert-run-or-rerun-test(#s(ert--stats :selector ... :tests ... :test-m
  ert-run-tests((not (or (tag :expensive-test) (tag :unstable))) #f(co
  ert-run-tests-batch((not (or (tag :expensive-test) (tag :unstable)))
  ert-run-tests-batch-and-exit((not (or (tag :expensive-test) (tag :un
  eval((ert-run-tests-batch-and-exit '(not (or (tag :expensive-test) (
  command-line-1(("-L" ":." "-l" "ert" "--eval" "(setq treesit-extra-l
  command-line()
  normal-top-level()
Test erc--check-prompt-input-for-multiline-blanks condition:
    Info: Opts: (+wb -sw), Input: "a", want: (a)
    (user-error "Process not running")
   FAILED   5/95  erc--check-prompt-input-for-multiline-blanks (10.525627 sec) at lisp/erc/erc-tests.el:1637


  Andrea