You changed
if (my $var) { ... }
to
if (...) { my $var; ... }

use strict;
use warnings;
use Devel::Peek;

my $ref;

if ((my $fred = 42), 1)
{
    $ref = \$fred;
    Dump($$ref);
}

Dump($$ref);
[download]

SV = IV(0x816a5cc) at 0x814f684
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY,IOK,pIOK)
  IV = 42
SV = IV(0x816a5cc) at 0x814f684
  REFCNT = 2
  FLAGS = (PADBUSY,PADMY,IOK,pIOK)
  IV = 42
[download]

A scope is created for if's curlies, but only a compile-time scope is created for the condition expression.

Btw, note the proper usage of Dump.