skip plugins that are bundled with the distribution

They are not installable and do not need to be included as prereqs.

Changes

@@ -2,6 +2,10 @@ Revision history for Dist-Zilla-Plugin-Prereqs-AuthorDeps
 
 {{$NEXT}}
 
+    [CHANGED]
+
+    - plugins that exist in the local build root are not added as prereqs.
+
 0.006     2016-05-02 11:06:55-04:00 America/New_York
 
     [CHANGED]

corpus/DZ/dist.ini

@@ -19,4 +19,6 @@ exclude = Dist::Zilla::Plugin::RemovePrereqs
 [RemovePrereqs]
 remove = MostlyHarmless
 
+[=inc::Foo]
+
 ; authordep Devel::Foo = 0.123

corpus/DZ/inc/Foo.pm

@@ -0,0 +1,5 @@
+package inc::Foo;
+use Moose;
+with 'Dist::Zilla::Role::BeforeBuild';
+sub before_build { 1 }
+1;

lib/Dist/Zilla/Plugin/Prereqs/AuthorDeps.pm

@@ -9,6 +9,7 @@ our $VERSION = '0.007';
 use Moose;
 use MooseX::Types::Moose qw( HashRef ArrayRef Str );
 use List::Util qw/min/;
+use Path::Tiny;
 
 use Dist::Zilla::Util::AuthorDeps 5.021;
 use Dist::Zilla 4;
@@ -81,6 +82,10 @@ sub register_prereqs {
     for my $req (@$authordeps) {
         my ( $mod, $version ) = each %$req;
         next if $self->_exclude_hash->{$mod};
+
+        (my $filename = $mod) =~ s{::}{/}g;
+        next if path($self->zilla->root, $filename.'.pm')->exists;
+
         $zilla->register_prereqs( { phase => $phase, type => $relation }, $mod, $version );
     }