Fix bug #13661 with w32-downcase-file-names and shell-command.

 src/callproc.c (Fcall_process_region): Make sure the XXXXXX part of
 the temporary file pattern is not downcased even when
 w32-downcase-file-names is non-nil.

src/ChangeLog

 2013-02-09  Eli Zaretskii  <eliz@gnu.org>
+	* callproc.c (Fcall_process_region): Make sure the XXXXXX part of
+	the temporary file pattern is not downcased even when
+	w32-downcase-file-names is non-nil.  (Bug#13661)
+
 	* xdisp.c (decode_mode_spec): Remove handling of %t.
 	* msdos.c (careadlinkatcwd): Remove.

src/callproc.c

@@ -1016,8 +1016,26 @@ usage: (call-process-region START END PROGRAM &optional DELETE BUFFER DISPLAY &r
   {
     USE_SAFE_ALLOCA;
     Lisp_Object pattern = Fexpand_file_name (Vtemp_file_name_pattern, tmpdir);
-    Lisp_Object encoded_tem = ENCODE_FILE (pattern);
-    char *tempfile = SAFE_ALLOCA (SBYTES (encoded_tem) + 1);
+    Lisp_Object encoded_tem;
+    char *tempfile;
+
+#ifdef WINDOWSNT
+    /* Cannot use the result of Fexpand_file_name, because it
+       downcases the XXXXXX part of the pattern, and mktemp then
+       doesn't recognize it.  */
+    if (!NILP (Vw32_downcase_file_names))
+      {
+	Lisp_Object dirname = Ffile_name_directory (pattern);
+
+	if (NILP (dirname))
+	  pattern = Vtemp_file_name_pattern;
+	else
+	  pattern = concat2 (dirname, Vtemp_file_name_pattern);
+      }
+#endif
+
+    encoded_tem = ENCODE_FILE (pattern);
+    tempfile = SAFE_ALLOCA (SBYTES (encoded_tem) + 1);
     memcpy (tempfile, SDATA (encoded_tem), SBYTES (encoded_tem) + 1);
     coding_systems = Qt;