Include ./lib in @inc when running dzil build if the distro starts with Dist-Zilla

I would assume that any dzil bundle or plugin distro wants to use itself
during building.

Author: autarch

Changes.md

@@ -1,3 +1,9 @@
+## 0.1.9 2021-01-08
+
+* If the distro name starts with "Dist-Zilla", then the distro's lib dir will
+  be included in `@INC` (via `dzil -I lib`) when running `dzil build.
+
+
 ## 0.1.8 2021-01-08
 
 * If a distro has a script named `dev-bin/install-xt-tools.sh` we now run this

tools/lib/T/BuildDist.pm

@@ -48,6 +48,17 @@ sub run {
 sub _build_dzil {
     my $self = shift;
 
+    my $content = path('dist.ini')->slurp_utf8;
+    my ($distro) = $content =~ /name\s*=\s*(\S+)/;
+
+    my @i;
+
+    # This assumes that any dzil-related module will use itself during dzil
+    # build.
+    if ( $distro && $distro =~ /\ADist-Zilla/ ) {
+        @i = ( '-I', 'lib' );
+    }
+
     # The working dir might be something like '~/project` and pushd can't
     # handle the '~', apparently.
     my $dir = $self->_pushd( $self->checkout_dir );
@@ -57,6 +68,7 @@ sub _build_dzil {
             $self->_system(
                 $self->_brewed_perl( $self->tools_perl ),
                 $self->_perl_local_script( $self->tools_perl, 'dzil' ),
+                @i,
                 'build',
             );
         },