Do not alter match data in Fcapitalize etc.

Without this patch, (capitalize "x") can alter the match data,
which is not what users expect.  Problem found by running
morse-tests-unnato-region in a stripped-down Emacs.
Perhaps ‘load’ should also save and restore the match data?
That would be a simpler fix, though arguably incompatible.
* src/lread.c (save_match_data_load): New function.
* src/chartab.c (uniprop_table):
* src/doc.c (reread_doc_file):
* src/eval.c (Fautoload_do_load):
* src/fns.c (Frequire): Use it.

1 files changed, 1 insertions, 4 deletions

diff --git a/src/eval.c b/src/eval.c
index 8f569949036..02a6c3555a9 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -2049,9 +2049,6 @@ it defines a macro.  */)
 
   CHECK_SYMBOL (funname);
 
-  /* Preserve the match data.  */
-  record_unwind_save_match_data ();
-
   /* If autoloading gets an error (which includes the error of failing
      to define the function being called), we use Vautoload_queue
      to undo function definitions and `provide' calls made by
@@ -2067,7 +2064,7 @@ it defines a macro.  */)
      so don't signal an error if autoloading fails.  */
   Lisp_Object ignore_errors
     = (EQ (kind, Qt) || EQ (kind, Qmacro)) ? Qnil : macro_only;
-  Fload (Fcar (Fcdr (fundef)), ignore_errors, Qt, Qnil, Qt);
+  save_match_data_load (Fcar (Fcdr (fundef)), ignore_errors, Qt, Qnil, Qt);
 
   /* Once loading finishes, don't undo it.  */
   Vautoload_queue = Qt;