psgi env: fix double encoding of path parts

Fix double encoding of path parts when parsing a PSGI env with a SCRIPT_NAME set.
Make sure path is decoded and unescaped as expected by to_string.

The test $env used in the regression test included is a stripped down version of the result of:

  use HTTP::Request::Common 'GET';
  use HTTP::Message::PSGI 'req_to_psgi';
  my $script_name = ...;
  my $path = ...;
  $env = req_to_psgi( GET( 'http://localhost:8080'.$script_name.$path ), SCRIPT_NAME => $script_name );

Author: Alexander Kuehne

lib/Mojo/Message/Request.pm

@@ -197,6 +197,7 @@ sub _parse_env {
     $base->path->parse($value =~ m!/$! ? $value : "$value/");
 
     # Remove SCRIPT_NAME prefix if necessary
+    $path->parts;
     my $buffer = $path->to_string;
     $value  =~ s!^/|/$!!g;
     $buffer =~ s!^/?\Q$value\E/?!!;

t/mojo/request_cgi.t

@@ -2,6 +2,7 @@ use Mojo::Base -strict;
 
 use Test::More;
 use Mojo::Message::Request;
+use Mojo::Util qw(encode url_escape);
 
 subtest 'Parse Lighttpd CGI environment variables and body' => sub {
   my $req = Mojo::Message::Request->new;
@@ -124,6 +125,25 @@ subtest 'Parse CGI environment with maximum message size' => sub {
     'right absolute URL';
 };
 
+subtest 'Parse CGI environment with SCRIPT_NAME set and path part with UTF-8 character' => sub {
+  my $req         = Mojo::Message::Request->new;
+  my $script_name = '/app/';
+  my $path_stub   = 'some/action/blub/';
+  my $part_utf8   = encode('utf-8', "\x{1d120}");
+  my $path        = $path_stub.url_escape($part_utf8);
+  $req->parse({
+    CONTENT_LENGTH  => 0,
+    PATH_INFO       => '/'.$path_stub.$part_utf8,
+    REQUEST_URI     => $script_name.$path,
+    QUERY_STRING    => '',
+    REQUEST_METHOD  => 'GET',
+    SCRIPT_NAME     => $script_name,
+    HTTP_HOST       => 'localhost:8080',
+    SERVER_PROTOCOL => 'HTTP/1.1'
+  });
+  is $req->url->path->to_string, $path, 'round tripping yields same path';
+};
+
 subtest 'Parse Apache CGI environment variables and body (file storage)' => sub {
   local $ENV{MOJO_MAX_MEMORY_SIZE} = 10;
   my $req = Mojo::Message::Request->new;