Not sure if this is your bug but you should set the patterns in single quotes for the case they include spaces.
You could change your line:

my $exclude = join ' --exclude=', '', @{$self->{patterns}};
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to:

my $exclude;
$exclude .= sprintf q{ --exclude='%s'}, $_ foreach @{$self->{patterns}
+};
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or:

my $exclude = join '', (map " --exclude='$_'", @{$self->{patterns}});
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