bug#38793: 27.0.60; completion-table-test-quoting fails in out-of-tree build

[Ken Brown]

In an out-of-tree build, the test completion-table-test-quoting from
minibuffer-tests fails as follows:

Test completion-table-test-quoting backtrace:
   signal(ert-test-failed (((should (equal (completion-try-completion i
   ert-fail(((should (equal (completion-try-completion input #'completi
   (if (unwind-protect (setq value-37 (apply fn-35 args-36)) (setq form
   (let (form-description-39) (if (unwind-protect (setq value-37 (apply
   (let ((value-37 'ert-form-evaluation-aborted-38)) (let (form-descrip
   (let* ((fn-35 #'equal) (args-36 (condition-case err (let ((signal-ho
   (let ((output x33) (input x31)) (let* ((fn-35 #'equal) (args-36 (con
   (let* ((x31 (car x30)) (x32 (cdr x30)) (x33 (car x32)) (x34 (cdr x32
   (let ((x30 (car --dolist-tail--))) (let* ((x31 (car x30)) (x32 (cdr
   (while --dolist-tail-- (let ((x30 (car --dolist-tail--))) (let* ((x3
   (let ((--dolist-tail-- '(("data/m-cttq" "data/minibuffer-test-cttq$$
   (let ((process-environment (cons "CTTQ1=ed" (cons "CTTQ2=et/" proces
   (closure (t) nil (let ((process-environment (cons "CTTQ1=ed" (cons "
   ert--run-test-internal(#s(ert--test-execution-info :test #s(ert-test
   ert-run-test(#s(ert-test :name completion-table-test-quoting :docume
   ert-run-or-rerun-test(#s(ert--stats :selector completion-table-test-
   ert-run-tests(completion-table-test-quoting #f(compiled-function (ev
   ert-run-tests-batch(completion-table-test-quoting)
   ert-run-tests-batch-and-exit(completion-table-test-quoting)
   eval((ert-run-tests-batch-and-exit 'completion-table-test-quoting) t
   command-line-1(("-L" ":../../emacs-27/test" "-l" "ert" "-l" "lisp/mi
   command-line()
   normal-top-level()
Test completion-table-test-quoting condition:
     (ert-test-failed
      ((should
        (equal
         (completion-try-completion input ... nil ...)
         (cons output ...)))
       :form
       (equal nil
              ("data/minibuffer-test-cttq$$tion" . 31))
       :value nil :explanation
       (different-types nil
                        ("data/minibuffer-test-cttq$$tion" . 31))))
    FAILED  1/1  completion-table-test-quoting (0.001261 sec)



In GNU Emacs 27.0.60 (build 8, x86_64-pc-cygwin, GTK+ Version 3.22.28)
  of 2019-12-28 built on moufang2
Repository revision: d915b8c3f19d6627b3f394c98a51c51e91d03062
Repository branch: emacs-27