Do a backup when forcing new file

bin/mkexec.pl

@@ -48,8 +48,10 @@ $cmds->{editor}->{run}  = "editor '%s'";
 ## ''' ##   # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #
 
 if (exists $bangs->{$type}) {
-    -e $name and not $force
-        or mkexec $name, mkbody($type);
+    $force and -e $name
+        and (defined `cp "$name" "$name~"` or die $!);
+    (not -e $name or $force)
+        and mkexec $name, mkbody($type);
     chmod $DEFAULT_MODE, $name;
     launch_editor $name;
 } else {