Ignore string properties when saving eshell history (Bug#28700)

* lisp/eshell/em-hist.el (eshell-write-history): Remove properties
before inserting history strings.
(eshell-read-history): Remove obsolete comment.
* test/lisp/eshell/em-hist-tests.el (eshell-write-readonly-history):
New test.

1 files changed, 3 insertions, 2 deletions

diff --git a/lisp/eshell/em-hist.el b/lisp/eshell/em-hist.el
index 1ab3c60b2c7..8084c126530 100644
--- a/lisp/eshell/em-hist.el
+++ b/lisp/eshell/em-hist.el
@@ -444,7 +444,6 @@ line, with the most recent command last.  See also
              (ignore-dups eshell-hist-ignoredups))
         (with-temp-buffer
           (insert-file-contents file)
-          ;; Save restriction in case file is already visited...
           ;; Watch for those date stamps in history files!
           (goto-char (point-max))
           (while (and (< count size)
@@ -488,7 +487,9 @@ See also `eshell-read-history'."
           (while (> index 0)
             (setq index (1- index))
             (let ((start (point)))
-              (insert (ring-ref ring index) ?\n)
+              ;; Remove properties before inserting, to avoid trouble
+              ;; with read-only strings (Bug#28700).
+              (insert (substring-no-properties (ring-ref ring index)) ?\n)
               (subst-char-in-region start (1- (point)) ?\n ?\177)))
           (eshell-with-private-file-modes
            (write-region (point-min) (point-max) file append