Revert make-text-button string copy

* lisp/button.el (make-text-button): Don’t make a copy of
a button’s string label.  This reverts the change made in
2020-05-17T05:23:28Z!eggert@cs.ucla.edu, which broke SLY.
Problem reported by João Távora in:
https://lists.gnu.org/r/emacs-devel/2020-06/msg00117.html
However, we’ll need a better fix for this once string
literals become contents, if SLY uses string constants
for text button labels.

1 files changed, 0 insertions, 1 deletions

diff --git a/lisp/button.el b/lisp/button.el
index a91b0482acd..3a6a6de774c 100644
--- a/lisp/button.el
+++ b/lisp/button.el
@@ -349,7 +349,6 @@ Also see `insert-text-button'."
          (or (plist-member properties 'type)
              (plist-member properties :type))))
     (when (stringp beg)
-      (setq beg (copy-sequence beg)) ;; In case BEG is not mutable.
       (setq object beg beg 0 end (length object)))
     ;; Disallow setting the `category' property directly.
     (when (plist-get properties 'category)