use do rather than require to load a mojo application

The return value of require is usually not a reasonable thing to rely
on, aside from it being true. The first time requiring a file, it will
return the value of the last statement in the file. The second time
requiring a file, it will return a simple true value.

Mojo was bypassing this problem by deleting the %INC entry for the file,
forcing it to always be loaded again. But the new module_true core
feature will cause require to always return a simple true value rather
than the last statement in the file. This does not apply to do though.

Switch to using do to be compatible with code using the new feature.

lib/Mojo/Server.pm

@@ -54,9 +54,9 @@ sub load_app {
     local @ARGS_OVERRIDE = @args;
 
     # Try to load application from script into sandbox
-    delete $INC{$path};
-    my $app = eval "package Mojo::Server::Sandbox::@{[md5_sum $path]}; require \$path";
-    die qq{Can't load application from file "$path": $@} if $@;
+    my $app = eval "package Mojo::Server::Sandbox::@{[md5_sum $path]}; do \$path";
+    my $err = $app ? undef : $@ || $! || "$path did not return a true value";
+    die qq{Can't load application from file "$path": $err} if $err;
     die qq{File "$path" did not return an application object.\n} unless blessed $app && $app->can('handler');
     $self->app($app);
   };

t/mojo/daemon.t

@@ -91,6 +91,15 @@ subtest 'Load broken app' => sub {
   like $@, qr/^Can't load application/, 'right error';
 };
 
+subtest 'Load app using module_true' => sub {
+  plan skip_all => 'module_true feature requires perl 5.38' if $] < 5.038;
+  my $daemon = Mojo::Server::Daemon->new;
+  my $path   = curfile->sibling('lib', '..', 'lib', 'myapp-module-true.pl');
+  my $app    = eval { $daemon->load_app($path) };
+  is $@,       '',                  'no error loading app';
+  is ref $app, 'Mojolicious::Lite', 'right reference';
+};
+
 subtest 'Load missing application class' => sub {
   eval { Mojo::Server::Daemon->new->build_app('Mojo::DoesNotExist') };
   like $@, qr/^Can't find application class "Mojo::DoesNotExist" in \@INC/, 'right error';

t/mojo/lib/myapp-module-true.pl

@@ -0,0 +1,15 @@
+use v5.38;
+use Mojolicious::Lite;
+
+app->config(script => $0);
+
+app->start;
+
+=head1 SYNOPSIS
+
+  USAGE: myapp.pl daemon
+
+   test
+  123
+
+=cut