my $git = Import::Git->new( dryrun => $dryrun );

around BUILDARGS => sub {
     my $orig  = shift;
     my $class = shift;

     my %args = ( @_ == 1 ? %{ $_[ 0 ] } : @_ );

     if ( !%args || $args{ 'dryrun' } != 1 ) {
         return $class->$orig( @_ );
     }
     else {
         return Import::Git::dryrun->$orig( @_ );
    }
};

DB<1> x Import::Git->new( dryrun => 1 )
0  Import::Git=HASH(0x2fd9210)
   'dryrun' => 1
  DB<2> x Import::Git->new()
0  Import::Git=HASH(0x301dbb8)
   'dryrun' => 0
  DB<3>

# change this:
   return Import::Git::dryrun->$orig( @_ );
   # to this
   return Import::Git::dryrun->new( @_ );