t/run/switches.t: touch up -s section

- move "bug id" comment where it was originally placed: before the
  "#!perl -s" test
- add GH ticket number and short description
- remove 2-arg open

Author: mauke

t/run/switches.t

@@ -155,9 +155,10 @@ $r = runperl(
 );
 is( $r, '21-', '-s switch parsing' );
 
+# Bug ID 20011106.084 (RT #7876 / GH #4554): -s on shebang line
 $filename = tempfile();
 SKIP: {
-    open my $f, ">$filename" or skip( "Can't write temp file $filename: $!" );
+    open my $f, ">", $filename or skip( "Can't write temp file $filename: $!" );
     print $f <<'SWTEST';
 #!perl -s
 BEGIN { print $x,$y; exit }
@@ -170,10 +171,9 @@ SWTEST
     is( $r, 'foo1', '-s on the shebang line' );
 }
 
-# Bug ID 20011106.084 (#7876)
 $filename = tempfile();
 SKIP: {
-    open my $f, ">$filename" or skip( "Can't write temp file $filename: $!" );
+    open my $f, ">", $filename or skip( "Can't write temp file $filename: $!" );
     print $f <<'SWTEST';
 #!perl -sn
 BEGIN { print $x; exit }