flaky php-project-root test in 1.21.x

[sten0]

Steps to reproduce:

wget https://github.com/emacs-php/php-mode/archive/v1.21.4.tar.gz
tar xf v1.21.4.tar.gz
cd php-mode-1.21.4
make test

I believe the test is failing because the release tarball does not provide something to match any of php-project-available-root-files.

…
   passed  56/58  php-mode-test-variables
Test php-project-root backtrace:
  signal(ert-test-failed (((should (string= (abbreviate-file-name defa
  ert-fail(((should (string= (abbreviate-file-name default-directory) 
  (if (unwind-protect (setq value-403 (apply fn-401 args-402)) (setq f
  (let (form-description-405) (if (unwind-protect (setq value-403 (app
  (let ((value-403 'ert-form-evaluation-aborted-404)) (let (form-descr
  (let* ((fn-401 (function string=)) (args-402 (condition-case err (le
  (lambda nil (let* ((fn-401 (function string=)) (args-402 (condition-
  ert--run-test-internal(#s(ert--test-execution-info :test #s(ert-test
  ert-run-test(#s(ert-test :name php-project-root :documentation nil :
  ert-run-or-rerun-test(#s(ert--stats :selector t :tests [#s(ert-test 
  ert-run-tests(t #f(compiled-function (event-type &rest event-args) #
  ert-run-tests-batch(nil)
  ert-run-tests-batch-and-exit()
  command-line-1(("-L" "." "-l" "php-mode-test.el" "-f" "ert-run-tests
  command-line()
  normal-top-level()
Test php-project-root condition:
    (ert-test-failed
     ((should
       (string=
        (abbreviate-file-name default-directory)
        (php-project-get-root-dir)))
      :form
      (string= "/build/php-elisp-ppwuU3/php-elisp-1.21.4/" nil)
      :value nil))
   FAILED  57/58  php-project-root
…

And here is the full backtrace from ert-run-tests-interactively (P.S. I've never seen such a long backtrace!): Wow, so long I have to attach it...
backtrace.zip

[zonuexe]

@sten0 Thanks!