patch 7.4.975

Problem:    Using ":sort" on a very big file sometimes causes text to be
            corrupted. (John Beckett)
Solution:   Copy the line into a buffer before calling ml_append().

src/ex_cmds.c

@@ -540,10 +540,11 @@ ex_sort(eap)
 	if (!unique || i == 0
 		|| (sort_ic ? STRICMP(s, sortbuf1) : STRCMP(s, sortbuf1)) != 0)
 	{
-	    if (ml_append(lnum++, s, (colnr_T)0, FALSE) == FAIL)
+	    /* Copy the line into a buffer, it may become invalid in
+	     * ml_append(). And it's needed for "unique". */
+	    STRCPY(sortbuf1, s);
+	    if (ml_append(lnum++, sortbuf1, (colnr_T)0, FALSE) == FAIL)
 		break;
-	    if (unique)
-		STRCPY(sortbuf1, s);
 	}
 	fast_breakcheck();
 	if (got_int)

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    975,
 /**/
     974,
 /**/