[Module::Build] problem with programmatic control of multiple builds

[Ray Z. <rz...@co...>]

I have an automated build, test and install process for a collection  
of in-house Perl packages* using a straightforward procedure which is  
basically ...

foreach my $dist ( @dist_list ) {
     my $dir = File::Spec->join('my_build_dir', $dist);
     chdir $dir  or die "could not change to $dir";

     $p = { <some build options> };

     my $b = Module::Build->new_from_context( %$p );
     $b->dispatch('build');
     $b->dispatch('test');
     $b->dispatch('install');
}

I ran into a problem when attempting to convert everything from using  
a slightly modified version of M::B 0.2608 to M::B 0.2801. The  
problem I am encountering has to do with the fact that $b- 
 >build_elements appears to be cumulative in the above loop, even  
though $b is being recreated. That is, if one of the Build.PL files  
has ...

     $b->add_build_element('foo');

... then all subsequent $dist's in the above loop will attempt to  
build foo elements even though the corresponding Build.PL does not  
mention foo anywhere.

I believe the %valid_properties closure in  
Module::Build::Base::ACTION_config_data is the culprit. Is this a  
bug? Shouldn't the list of build_elements (all config data, in fact)  
be an object property as opposed to class data?

Any suggestions for a workaround to start over with a completely  
fresh, clean M::B at the beginning of each loop?

Thanks,
   - Ray

* Consisting of a base package A and add-on packages B, as described  
in yesterday's post "M::B subclass .pm file locations".