Check before using bleeding edge ERT sym in Eglot tests

Else, these tests won't run on Emacs versions that Eglot runs on, like
26.3.

* test/lisp/progmodes/eglot-tests.el
(eglot--call-with-tramp-test):  check for
ert-remote-temporary-file-directory before using.

1 files changed, 3 insertions, 1 deletions

diff --git a/test/lisp/progmodes/eglot-tests.el b/test/lisp/progmodes/eglot-tests.el
index 7a90d68d213..9cb6befa993 100644
--- a/test/lisp/progmodes/eglot-tests.el
+++ b/test/lisp/progmodes/eglot-tests.el
@@ -1262,7 +1262,9 @@ macro will assume it exists."
   (let* ((tramp-remote-path (cons 'tramp-own-remote-path tramp-remote-path))
          (tramp-histfile-override t)
          (tramp-verbose 1)
-         (temporary-file-directory ert-remote-temporary-file-directory)
+         (temporary-file-directory
+          (or (bound-and-true-p ert-remote-temporary-file-directory)
+              temporary-file-directory))
          (default-directory temporary-file-directory))
     ;; We must check the remote LSP server.  So far, just "clangd" is used.
     (unless (executable-find "clangd" 'remote)