Workaround for bug in Parse::CPAN::Meta "YAML" parser

The Parse::CPAN::Meta parser is used by the Test::CPAN::Meta module
that the Plugin::MetaTests plugin uses.

The parser is a extremely fragile parser and chokes with valid YAML,
like a single element list:

    author:
    - Pedro Melo <melo@cpan.org>
    generated_by: Dist::Zilla::Plugin::MetaYaml version 1.091260

We now flatten the author entry if it is a single element list.

Signed-off-by: Pedro Melo <melo@simplicidade.org>

lib/Dist/Zilla/Plugin/MetaYaml.pm

@@ -34,6 +34,23 @@ sub gather_files {
   $meta = Hash::Merge::Simple::merge($meta, $_->metadata)
     for $self->zilla->plugins_with(-MetaProvider)->flatten;
 
+  # Flatten lists with a single element
+  # workaround for simplistic Parse::CPAN::Meta YAML parser
+  # used by Test::CPAN::Meta used by Plugin::MetaTests
+  # We limit this to the authors entry for now, although a general
+  # solution could be used
+  # 
+  #   while (my ($key, $value) = each %$meta) {
+  #     if (ref($value) eq 'ARRAY' && @$value == 1) {
+  #       $meta->{$key} = $value->[0];
+  #     }
+  #   }
+  if (exists $meta->{author}
+      && ref($meta->{author}) eq 'ARRAY'
+      && @{$meta->{author}} == 1) {
+    $meta->{author} = $meta->{author}[0];
+  }
+
   my $file = Dist::Zilla::File::InMemory->new({
     name    => 'META.yml',
     content => YAML::XS::Dump($meta),