As long as all of your lines that are definitions start with whitespace, the following will work; this is because when the template wraps, it won't prefix the (wrapped) line with anything. This allows us to know what's a wrap, and what's not. No special handling of '=' signs needed.

use Config::General;
use Data::Dumper;

undef $/;
my $file = <DATA>;

$file =~ s/\n(\S)/ $1/g;

my $config = Config::General->new(-String=>$file);

print Dumper {$config->getall};

__DATA__
  foo                = Yes
  bar                = 0
  blort              = 
  home_url           =
http://www.foo.com/some/really/long/url?foo=bar
[download]

Produces:

$VAR1 = {
          'bar' => '0',
          'boo' => '',
          'blort' => '',
          'foo' => 'Yes',
          'home_url' => 'http://www.foo.com/some/really/long/url?foo=b
+ar',
        };
[download]