p2.p6

my $root := $library_root.IO.absolute;
$fh.write: $sth.allrows.map(
    *.subst(/^ 'file://' /, '').subst(
      :g, "+", "%2b"
    ).&uri-unescape(:enc<utf8-c8>).IO.relative($root) ~ "\n"
).encode: 'utf8-c8'

p6.p6

my $root := $library_root.IO.absolute;
$fh.write: $sth.allrows.map({
    uri-unescape( :enc<utf8-c8>,
      .subst(/^ 'file://' /, '')
      .subst(:g, "+", "%2b")
    ).IO.relative($root) ~ "\n"
}).encode: 'utf8-c8'

p7.p6

my $root := $library_root.IO.absolute;
$fh.write: $sth.allrows.map(
    *.subst(/^ 'file://' /, '')
    .subst(:g, "+", "%2b")\
    .&uri-unescape(:enc<utf8-c8>).IO.relative($root) ~ "\n"
).encode: 'utf8-c8'